Understanding the Spirits
Pact Magic Unbound: Grimoire of Lost Souls is one of the highlights of Radiance House's line of products, but it's definitely a system that requires some understanding and expertise if you're going to make the best use of it. This guide is going to take a look at the 100+ spirits that appear in the Grimoire of Lost Souls, with notes on understanding how these character options actually work and how you can get the most of them. In effect, this offers a bite-sized look at each spirit so you don't have to read all their abilities to know what might be good for your build. It's still a lot of content, but that's because there are so many spirits to choose from.
Note: This page works best if you skim the spirits themselves. Most start with a brief description of their general style, which can help you figure out if it might be worthwhile to read more of. It is quite a lot of content to read straight through, so this page is designed to help minimize that unless you really want to do it. We don't expect you to read everything here.
The first thing to know about spirits is that each spirit is geared towards a different style of play. The defining feature of a spirit is their Major Granted Ability, which provides a specific power that can generally be used once every five posts. The normal length of combat can vary by table, but 4-5 rounds per-fight isn't unusual, so we can safely say that a Major Granted Ability is essentially a power you can use once or twice a fight.
Supporting the Major Granted Ability are four Minor Granted Abilities that enhance the main theme of the class in some way. These abilities tend to have a roughly even split between passive bonuses and active abilities (often spell-like powers usable a set number of times per-day). For even more complexity, the Vestigal Bond of a class can change some of the abilities you get and offer you something else.
That's already a lot to get through, so let's see how this actually plays out. Marat, the Guardian of Shields, is a first-level spirit (so a character could start play with them). Their major ability allows them to swap places with an ally in 30 feet as a move action, without provoking an attack of opportunity in doing so. This allows you to do things like swap a low-AC character to safety if the party gets ambushed from behind, pull an exposed ally to the safety of the group if they're being hurt too much, or leap forward to attack an enemy after an ally has gone. It's a very potent ability, but you're only going to get good use out of it if your group knows you have it and accepts the use of it.
Marat's minor abilities include gaining the Bodyguard feat, equipping Marat as armor that scales with your level, the use of two warding-type spells, and proficiency with armor. But wait, not every class wants to wear heavier armors! Casters with somatic components, we're looking at you. Marat's Vestigal Bond lets you get a permanent Mage Armor instead, so even casters can make good use of this defensive option (although they're more likely to teleport themselves out of danger with their major ability, rather than rescuing an ally).
The key thing to understand here is that while spirits are useful as-is, you're really only going to get the most value from them if you truly understand their abilities and figure out the best way to make those powers work in your game. Not every spirit is necessarily going to be a good option for each game (or character), but there's enough variety that a binder can be a suitable choice for pretty much any role in any game. There's a heavy occult feel to the system, but it's not hard to reflavor it to something more specific, such as a character channeling the power of angels, heroes, or eldritch things from the void. In fact, you almost have to do this if you're playing one of the archetypes, since most of them restrict you to spirits from a particular theme.
Finally, throughout the guide below, you'll notice that I often reference "primary" and "secondary" spirits. This is not a mechanical element - rather, it's about the way Pactmakers can bind multiple spirits to themselves. A "primary" spirit is one that you might want to bind every day because it's so generally useful. A "secondary" spirit isn't really good enough to bind all by itself (so non-Pactmakers probably want to avoid them), but that may be useful in particular games, situations, or as extra options beyond the main focus you've decided to have for a day. Being secondary isn't necessarily a bad thing - you still have to deal with your action economy, and however 'strong' a spirit may be, it isn't very useful if you don't have the actions necessary to use it.
Finally, spirits can be bound in combinations that don't easily fall into the primary/secondary setup. Don't think that you HAVE to have a 'main' spirit, because you don't. Pactmakers are an insanely flexible class, and it's best to keep your mind open to your options.
Focus of the Spirits
Level 1 Spirits
Achaeolus - Movement
Achaeolus is built around movement. The major ability provides a bonus when you're charging enemies, and minor abilities include things like bonuses to your swim speed, controlling water to push foes around, and creating Obscuring Mists to reduce your foes' vision and discourage their movement. If you don't have a natural weapon, you can essentially turn yourself into a minotaur and gore enemies - alternately, you can swap that for an Auroch animal companion to ride and navigate terrain.
Aza'zati - Generalist
Aza'zati is something of an adventurer's spirit. His major ability allows you to deal scaling acid damage in a 30-foot cone (with added damage over time if you get empowerment), while his minor abilities include help bluffing and persuading, finding treasure, fitting through small spaces, and improving your natural defenses. In other words, he has a little bit of things that come up fairly regularly - he may not be phenomenal in one area, but you'll probably end up making regular use if he's equipped. Note that he's a Lawful Evil spirit, so Chaotic Good adventurers will have a harder time binding him. The ability to swap the shrinking spell for a viper familiar is worth considering, since that's a power not likely to see too much use.
Cave Mother - Generalist
Cave Mother is similar to Aza'zati in that she has something of a general adventurer focus, although you'll have to think carefully about when to use her abilities. Her major power hits all targets within ten feet of you - including allies - but also causes things it hits (including creatures) to be set on fire. No saving throw is mentioned here, making this a fairly reliable effect, but also requiring you to be away from your party to use it well. That leans more towards characters with good defenses than anything else. Her other powers are mostly utility - help with bluffing and hiding things, the use of Goodberry (as the spell), and the ability to cast True Strike are probably the highlights, but she also gives you access to Undead Bane weapons for a few rounds a day. That can be quite powerful during the early levels, and makes Cave Mother best suited for martial-type binders.
Coralene - Social
Coralene is primarily a social spirit, with her major ability granting short-range teleportation. Her minor abilities include the ability to Command enemies, help with disguise and stealth, and the ability to avoid being tracked. She also allows you to strike as if you had a silver weapon, which can be quite useful for overcoming the DR of certain foes. She's not too useful outside of her specialty, though, so you'd definitely want to limit your use of her to times when you expect social challenges and stealth to be the main issue of the day.
Dantalios - Movement
Dantalios is another movement-oriented spirit, and synergizes well with Achaeolus if you've gained the ability to bind multiple spirits. His major ability gives a +30 bonus to one type of movement speed you have, and he passively provides another +5 while extending the range you can charge at. His lesser abilities include help hurling things and grappling foes. Now, all together, Dantalios doesn't actually give you too much to do to others - he's all about helping you get to your destination, and you'll need to look at your other abilities for things to do once you arrive.
Eos Dei - Battlefield Control
Eos Dei is primarily a mind-affecting battlefield control spirit. His major ability can let you scramble a target's initiative, which has the potential to let an ally act faster or delay a foe for a little while. This is somewhat random, but the Capstone lets you apply a modifier and get a little more control over the result. It's riskier than most major abilities, but if used at the right time, it could give your party an edge. Eos Dei's other abilities include applying penalties to much of what foes will do (as a mind-affecting emotion power, so don't plan to use it on undead), hypnotizing foes, and sealing memories. Time Sense is basically an amusing extra that will almost never come up, though it could be used to enact a plan that requires you to do something at a set time.
Forash - Generalist
Forash is a major figure, lore-wise, claiming to essentially be mortals' source of Pact Magic. That provides some interesting roleplay opportunities for your GM to work in, but ability-wise, he's fairly potent for a first-level spirit. That said, he does have a bit of a combat focus. The major ability functions as a fiendish Summon Nature's Ally (with all the flexibility that entails), while his minor abilities include invisibility, bonuses on knowledge checks (less relevant for Pactmakers, who tend to be really good at that, but useful for others), and the ability to deal a small amount of sonic damage to foes. The real use of that ability is deafening spellcasters - most others won't be affected too badly. Passively, Forash also messes with enemies' ability to ready actions.
The drawback, of course, is that he's pretty obviously evil, and many of the powers can be hard to use in civilized regions. Keep that in mind before you start relying too heavily on him.
General Hessant - Martial
General Hessant is a warrior spirit, best-suited for martially-inclined binders. His major ability knocks foes prone (with a Reflex save to avoid, mind you), and the Capstone gives it a chance to entangle foes as well. This is great for interrupting a powerful opponent and letting the rest of your party pile on. His other abilities include resistance versus fear effects, dazing foes, automatically empowering any longsword you wield (and giving you proficiency, but anyone using him probably has that already), and a bonus on Intimidate and Sense motive if you want to interrogate captives or something. If you don't plan to fight yourself, you can trade the longsword buffs for a mount.
Gwenolyn's Ghost - Mind Control
As the name suggests, Gwenolyn's Ghost is a rather spectral spirit, and generally emphasizes mind-control and general spookiness. Unlike Eos Dei, however, Gwenolyn's Ghost has more of a supporting role. The major ability can daze foes - although as a mind-affecting emotion/phantasm power, many creatures will be resistant or immune - while a minor ability can inflict three different levels of fear. Aside from that, Gwenolyn's Ghost can also let you use Mage Hand (complete with going through solid objects), offers a passive bonus to Bluff and Diplomacy, and allows you to speak with dead creatures of close alignments. If you don't expect to make foes afraid very often, you can swap that power for a pony companion.
Jacques Gaston - Performance
Jacques Gaston is a performance-based spirit. The major ability is a standard-action attack (melee or ranged, but you have to threaten them - an unusual limit) that deals extra damage to foes and naturally stacks well into a Vital Strike build. Jacques Gaston also gives you use of Moment of Greatness, turns every weapon into a performance weapon, bonuses to all three social skills (and use of some of their abilities as move actions - feinting to render foes vulnerable to your stab is a very solid combo here), and a Vestigal Audience that turns every combat into a performance. If you're a little worried about that, you can swap it for an aura that makes it easier to flank foes and accurately hit them with your strikes.
Jacques Gaston is definitely a combat-focused spirit, but the social skill buff is a big one, and he might well be worth taking along in situations where you'd like to talk things out but also want to be ready to break some heads if things go sour.
Marat - Defense
Marat was described at the start of this post - and he hasn't changed. As a highly defensive spirit, Marat is built around protecting yourself and others, complete with the ability to summon and use armor (or Mage Armor, if you need to cast spells with Somatic components) and trade places with allies to get someone out of danger.
I don't know that he's good to keep as a main spirit forever, but tank characters will probably find him to be a valuable choice at the start of the game - at least until they can afford to just buy some better armor and swap Marat for another spirit.
Milo of Clyde - Investigation
Milo is an interesting spirit - although he's best used for cases where skill and a deft touch are needed more than raw power. His major ability gives you a scaling bonus to AC and Saving Throws for a round as an immediate action, and while it isn't much at first, it can grow to a pretty big bonus later on. He also gives bonuses for Disable Device and Sleight of Hand (plus disabling magic traps as if you were a rogue!), as well as Perception, Sense Motive, and Survival. Seriously, if you're trying to track down and question people, this is the spirit to do it with. Another minor ability can "encourage" people to tell the truth, while the last minor ability offers proficiency with crossbows and firearms, as well as bonuses to their reload speed. He doesn't actually summon weapons or ammo, though, so you'll have to bring your own - or trade it for a ferret familiar, which is probably a better option unless you plan to use those weapons.
Sevnoir - Fear
Sevnoir is all about creative use of fear. The main power strikes all foes (including, alas, allies) with a chance of being shaken for several rounds, and gives you an excellent charge speed to attack foes with. It's also easier to demoralize foes - and regardless of how you make them afraid, you can heal damage if you strike foes who are suffering a fear effect. As a defensive measure, you can also gain concealment for a short time.
Sevnoir isn't bad on its own, but it's most potent when it's used together with another spirit. Achaeolus and General Hessant, in particular, synergize fairly well with movement and can offer useful bonuses.
Verbose - Communication
As the name suggests, Verbose is something of a utility spirit focusing on communication. The major ability allows you to protect yourself with an illusion (though you have to be good at Stealth), while minor powers include the ability to temporarily learn languages, a bonus to Diplomacy checks, and a joke that dazes foes for a round. Many of Verbose's abilities also work on animals, and if you're not feeling very funny, you can swap that for any animal companion a Druid can have (and that's a LOT of flexibility).
Verbose is also harder to bind well than most first-level spirits - and while she's not very good as a main spirit, she's a solid secondary choice if you expect to encounter entities whose language you know of but don't normally speak. She's also a Starless spirit, which means most non-Pactmakers can access her. If nothing else, she's probably worth researching just in case.
Vishgurv - Generalist/Amphibious
Vishgurv is a curious spirit, with a major ability whose effects won't be seen much because they're something of a curse - although Staggered isn't too bad of a condition to inflict on anything with a low Fortitude save. More usefully, however, Vishgurv provides the amphibious subtype (letting you breathe water and air alike, plus a swim speed) and allows you to transform into a Skum, giving a growing bonus to Strength and Constitution and a penalty to Charisma. Pact of Servitude can serve as a free reincarnate - though you may need another resurrection, because if you cancel the pact with him over the next year and a day, you die again - but more usefully, he gives bonuses on Spellcraft and Use Magic Device, plus the ability to act as if you had Sorcerer/Wizard spells on your spell list for the purpose of seeing if you need to make UMD checks. In an item-heavy campaign, a rogue-type character might find this very useful.
Overall, Vishgurv's potential is determined mostly by how you employ him. The transformation is a nice alternative to Rage abilities (although it stacks with those!), useful for most martial characters. The other abilities require you to have gear on-hand, suspect you're going to die, or be planning some kind of underwater adventure - none of which are particularly common. In other words, he's situational - either very useful or not at all. I'd definitely research him just to get the option of being amphibious, though, because that's much better than a simple water breathing spell if you plan to be down a long time.
Level 2 Spirits
Al'Kra - Fear/Movement
Al'kra is a spirit that essentially turns you into Slenderma- I mean, into something of an assassin. The major ability allows you to inflict Shaken (the weakest form of fear) without a save, along with some nonlethal damage and the loss of any immunity to fear unless it makes a save or is mindless. It also has a chance to disrupt spells with verbal components if you hit the capstone - either way, this is more of an opener than a finisher. Minor abilities include the chance to inflict a more severe form of fear (with a will save), a small bonus on damage rolls, use of a blur effect, and the ability to teleport when you're concealed.
Al'kra tends to work best with single strikes - the last minor ability can make foes flat-footed against you, and the more damage rolls you make, the better. There's some definite utility for being able to warp when you want to a few times per day, but Al'kra is mainly a battle spirit and is most useful when used as such.
Hollow Eyes - Grappling
Hollow Eyes is a spirit designed around grappling foes. The major ability allows you to hit a foe with Confusion (Will negates), and the minor abilities allow you to transform into a gargoyle and grab foes as you fly past. You count as one size category larger for this - a helpful buff - and the gargoyle form comes with useful feats to make this easier. You also have the Grab ability on your gargoyle's talons, so you won't draw attacks of opportunity as easily.
The other abilities are mostly useful add-ons. One minor ability allows you to disguise yourself - with the potential of turning into a specific individual if you have their corpse - while the other lets you provide fast healing to yourself for awhile. That's not useful in combat, but you can do it enough times per day to heal a lot of the damage you might take.
Hollow Eyes is particularly solid as a 'surprise attack' kind of spirit, where you can ambush foes and carry them off before they can effectively react. You can do similar things in a normal combat, but you may not be using the spirit's abilities to the fullest if you let others get the drop on you.
Humble Ohbal - Teleportation
Humble Ohbal is a utility spirit with a focus on teleportation. His major abilities allows you to warp allies and/or enemies around the battlefield, setting enemies up for flanking and allies for full attacks. He also allows you to gain resistance to elemental damage, a feather fall effect, the ability to converse with elementals, and nourishment that stops you from needing to eat or drink. (Note that Pactmakers can get something similar with any spirit.) He also allows you to summon genie steeds - mounts for the party are good at first, but at higher levels, they can plane shift you as well. If you don't need mounts at the moment, you can swap them for an elemental familiar.
Imitreyes - Slowing
Imitreyes is a mind-affecting spirit, with his major ability creating a fog cloud that puts creatures to sleep while they're inside it. Yes, it affects your allies (but not you or a vestigal companion), so it's most effective if you use the time to set up something more useful for your party - say, blanketing the target area with area-of-effect powers. He also gives you the ability to make melee touch effects that deal Dexterity damage (no save), resistance to critical hits and sneak attacks, a chance to give a Suggestion to a creature, and the ability to read thoughts.
These abilities are varied enough to be more of a supplement for your actions than a main focus. To put it another way, Imitreyes is decent at creating a setup for you to do something else, but you need to have a plan for the follow-through to get the most out of him.
Lady Jarah - Performance
Lady Jarah is a performance-based spirit, but acts in more of a supporting role. Her major ability allows you to fascinate foes for a round - although you have to hit the Capstone Empowerment if you want to affect creatures with more hit dice than your binder level. She also provides access to a high number of languages, a Sanctuary spell-like ability with enough uses to be cast for every combat, a scaling self transformation, and a bonus on Bluff and Perform (Oratory). All together, she's really more of a social spirit, good for distracting segments of crowds or lying your way through a situation. The transformation is a good backup if things go wrong, but not good enough to bind her just for that.
Lord Foxglove IV - Finesse
Lord Foxglove IV focuses on making fatal strikes, especially as a Dexterity-focused character. His major ability allows you to inflict a random minor or major spellblight (which tends to wind up being either very useful or not at all), but he also gives Weapon Finesse, doubles the critical range of your weapons, and allows you to paralyze foes and make them easy to finish off. If you'd rather be a bit subtler, you can lay a mark on foes that gives them a penalty to saving throws against your charm and compulsion effects (a good setup for paralyzing them!), and a free bag of holding as long as you're bound to him.
Moy - Mind Control
Moy is another mind-controlling spirit, with a major ability that allows you to wreck someone's Charisma score - which is very useful against Cha-based casters if you can get through their Will save and not very good against most others. She also allows you to give Suggestions and Lesser Geases, entrall the weak-willed, or generate a simulacrum of yourself as a vestigal companion. On the subtler side, Moy provides bonuses to Know History, Spellcraft, and UMD, as well as a deflection bonus to your AC if you're unarmored and have a good Charisma score.
Functionally, this makes Moy another spirit who works best when she's in a supporting role, especially if you're expecting to face social situations and want to use mind-control on others. She's probably not the best choice unless you are expecting to face a lot of social situations, though - most characters will find other spirits to be more helpful.
Mute Sylvus - Ranged Attacks
Mute Sylvus is similar in many ways to a number of the other 'fast' spirits, like Dantalios. However, Mute Sylvus focuses on ranged attacks instead (thanks to proficiency with Longbows and Shortbows, plus free use of the Precise Shot feat), and he further improves your outcomes by providing a scaling bonus on attack and damage rolls. The capstone here is a fairly powerful one, improving your critical damage by another multiplier. His minor abilities include a flat bonus to your base speed (to help stay away from foes as you attack them), as well as good use of improvised weapons if you don't have a bow handy. A bonus to Perception and Survival rounds out the list.
It's also worth taking a look at the Vestigal Bond here. This is a curious one that allows you to treat one of your allies as your vestigal companion for the purpose of sharing granted abilities. You'll lose the improved speed, but your ally will be able to improvise weapons, spot traps better, use bows, or get that bonus against enemies... and if you hit the capstone, you could really empower a crit-focused ally.
Pevwyrn Pervon - Alchemy
Pevwyrn Pervon is an alchemist spirit. His major ability is the power to hurl a bolt of acid that can linger and deal damage over time. It's not a huge amount of damage, but the capstone improves it by 50%. More usefully, one of his minor abilities can change the element of the damage done, which is pretty handy for things like shutting down some forms of regeneration or taking advantage of elemental weaknesses.
The most useful minor ability is the ability to create alchemical drinks, turning vials of water into extracts and offering a variety of useful boons. His other abilities include resistance to fire damage and a bonus on two Intelligence-based skills of your choice, ideal if you need to identify foes and figure out what they're weak to. All in all, this is definitely a spirit for those who know what's ahead and want to be prepared.
Note that you can't give your extracts to others unless you give up the ability to change the type of energy damage you do.
Prince Oszen - Generalist
Prince Oszen is a flexible, generalist spirit - one of the best of this level, in fact, and definitely worth researching if you can bind him at all. His major ability essentially causes foes to lose their next turn of actions - a serious impediment if they fail their will save against it - and the Capstone makes it even more potent by limiting them even on a successful save. His minor abilities include bonuses on Know Engineering and Perception (the most-rolled skill in the game!), free checks for hazards even if you aren't paying attention, a polymorph that includes a burrow speed so you can go underground, some minor healing, and the ability to create pits around foes. Alternately, you can trade the polymorph for a humanoid follower. All-in-all, there's a lot to like with this one, and Prince Oszen may well be worth being your default spirit at this level.
Salendrios - Martial
Salendrios is a combat spirit with a good balance between offense and defense. The major ability allows you the chance to negate or outright reflect a hostile spell (with a capstone providing a big bonus if you're a low BAB character), and minor abilities that let you pick from a variety of domain powers, a ranged touch attack you can make multiple blows with (and that basically no creature can resist), and proficiency with the sawtooth saber - y'know, if you can get ahold of one. You can also detect others' religions, which isn't likely to see regular use but could be helpful in some corner cases.
Salendrios is pretty valuable for characters worried about facing a foe they normally wouldn't have a way to oppose, and the more martially-inclined characters will want to take a look at him.
Shelassik - Aquatic
Shelassik is an aquatic spirit, with their major power granting a rage-like effect and some adaptations to let you move around more freely underwater. You can also use certain weapons without penalties underwater, make foes afraid, or gain a shark as a companion. That said, Shelassik is probably most useful when paired with a spirit like Vishgurv, since you'll get a straight bonus to your movement and the two spirits combo well. As such, Pactmakers are likely to get more use from Shelassik than other binders.
Taios - Generalist
Taios is another generalist spirit - and quite a potent one, as it happens, but geared more towards parties of evil characters. The major ability is very similar to a Mythic Surge, allowing you to roll a dice and add the result to most rolls and checks. The Capstone, in fact, allows you to expend the major ability for a longer time to regain the use of mythic power. His other abilities include a powerful adaptation effect (endure elements, no need to eat or drink, fire resistance, and two visual immunities), help using the flachion and shortbow, bonuses to Perception and Survival, and favored terrain as if you were a ranger. The Vestigal Bond trades out the major ability - a rarity for spirits - in favor of a polymorph effect offering a fairly sizable bonus to AC and use of the Anarchic and Unholy abilities on your weapons. Not something to do in civilized society, but that's a pretty serious buff if you're going up against lawful and/or good foes. (It's especially good for evil campaigns.)
Tyrant Cromwell - Offense
Tyrant Cromwell is a heavy attack spirit, although the characters who can get the most use from him are already likely to be good in combat - in that sense, he's best thought of as a spirit to change your offensive style. His major ability includes a bonus to Strength - scaling up over time, with a capstone that lets it stay on far more often - and minor abilities that include protection from others detecting your alignment, a deflection bonus to your armor class, the benefits of Power Attack and Vital Strike (later Improved Vital Strike), and skill with a trio of nasty weapons.
All things considered, Tyrant Cromwell is a lot like Taios in that he's probably best for evil campaigns, but other games could still see some use out of him. He may be worth learning just for the hidden alignment effect, which can help if you're going into a heavily-secured area.
Ubro - Healing
Ubro is a healing spirit, with a variety of ways to safeguard allies. The major ability provides some temporary hit points for a minute - so you can't just leave it on them before each battle - and he also provides Channel Energy a few times a day (healing only), an easy way to determine the health of creatures, bonuses on Heal checks, and a small amount of Damage Reduction. You can trade the DR for the ability cause harm to both undead and evil outsiders with your channeling, which is probably worth doing in campaigns featuring either as enemies.
Ubro is definitely worth researching if you have the ability to bind him - you may not use him every day, but he's a solid secondary choice for Pactmakers and likely to see at least some use.
Level 3 Spirits
Cornelius Button - Alternatively Offensive/Supportive
Cornelius Button is a flexible, Jekyll-and-Hyde sort of spirit. He has two manifestations - Light Cornelius and Dark Cornelius, and which one you get depends on the result of your binding check. You are, however, able to change which one you're bound to in a one-hour process - which you can do at the start of the day to get the one you want, or sometime later in order to adapt to a situation.
Light Cornelius is more supportive, with a major ability that heals targets in a 20-foot cone, the ability to summon a swarm of crickets (as a rat swarm), and potentially summon a giant cricket companion.
Dark Cornelius is more offensive, with a major ability that can poison foes, the ability to summon a swarm of butterflies (as a bat swarm), and potentially summon a giant butterfly companion.
Both versions can create a Calm Emotions effect and create seedling bombs that can be hurled as a splash weapon and benefit from Alchemist Discoveries you have access to. This is probably the main draw of Cornelius Button - most of the other things he can do are done better by other spirits, but if you're expecting to face swarms of enemies, the seedling bombs will wreck them as long as you have uses left.
The Crystal Lady - Support/Battlefield Control
The Crystal Lady is a supporting and battlefield control spirit. Her main ability gives you a scaling boost to the most common types of d20 rolls - and that can be very high at upper levels - while the minor abilities allow you to sicken foes, use Hypnotic Pattern (with a higher HD cap!), and produce light that can be strengthened. Her Vestigal Bond lets you transfer a minor granted ability to an ally - which can be quite useful for buffing up your team and is worth considering.
That said, she's also unusual in that she applies drawbacks to you - you get the Clouded Vision curse of the Oracle (although it does get the improvements of higher levels), and you have to make a will save in order to lie. This is a balance for the potency of the major ability, so carefully consider whether or not you feel the benefit here is worth the cost.
Forty-Two - Constructs
Forty-Two is a construct-focused spirit. The main power deals a high amount of damage to constructs and objects, half the amount to half-constructs, and minimum damage to creatures. The Capstone - which you definitely want - improves the damage to half-constructs and other creatures. This ability is, overall, quite potent if you need to break through something and have time to do it in, although it's less useful when you're in a hurry. Also, the Capstone won't be easy to get on a regular basis until higher levels, so Forty-Two's true usefulness may not show up for you right away.
The minor abilities include the ability to cast Augury several times per day (I feel this was inevitable, really), as well as the ability to control constructs, a bonus to all Int skills you're trained in, and acquisition of the half-construct subtype (meaning a +2 bonus versus effects like disease and poison, no need to breathe, eat, or sleep unless you want to... and lack of ability to be resurrected, a drawback you'll need to be careful about).
Ghato'Kacha - Tanking (vs Melee)
Ghato'Kacha is a spirit of endurance, starting with a major ability that allows you to interrupt a foe's attack and strike them for the same amount of damage instead - although you have to be able to make an unarmed strike against them, limiting the usefulness against range attacks. This is, of course, more useful the more powerful your opponent is. The goal, of course, is to try and take your foe down before they can take you down.
The minor abilities provide help with finding evil outsiders, automatic stabilization if you go below 0 HP, proficiency with various hammer-type weapons (or a tiger companion), and finally, a way to paralyze foes that you're currently grappling. This makes for good synergy with Dantalios and/or Hollow Eyes if you're playing a Pactmaker, though enemies get a Will save and can only be targeted by it once a day.
For defense versus ranged attacks, see Kaiya (below).
Iona Ophid - Tanking
Iona Ophid is a defensive spirit, with a major ability that creates a Globe of Invulnerability (and a Capstone that can drastically extend the length your barrier is up). Minor abilities include the ability to Scent creatures and magic auras, a bonus to Diplomacy and Handle Animal on certain targets, bonuses to AC and saves versus poison, and the option to select a certain number of arcane spells from the Enchantment, Evocation, and/or Illusion schools. This is quite potent, and remains so even as you continue to level... although the limit of half your maximum spirit level for deciding which spells you can learn means that only binders who can reach 9th Level spirits will get the full use of this power. This ability also means that any Binder who can form a pact with Iona Ophid should probably learn how to do so.
Kaiya - Tanking (vs Ranged)
Kaiya is another defensive spirit, but unlike Ghato'Kacha, she's better against ranged attacks than melee - and that's pretty much the deciding factor between the two if your character has the choice. Kaiya's major ability destroys projectiles by turning them into birds (so they're TOTALLY gone, and can't be retrieved by you or your enemies), functioning much like Deflect Arrows. She also grants help with detecting evil, improved odds versus effects that reduce ability scores (very valuable if you know you'll be facing a lot of that!), bonuses to Diplomacy and Perform, and use of Shield Other and Protection from Evil effects.
I probably wouldn't pick her as a main spirit unless I expected to face a lot of ability damage/drain in one day, but she's a pretty solid choice as a secondary spirit (if perhaps not quite as good defense-wise as Marat - but then, she does have more utility options than Marat).
Muse Istago - Buffing/Illusion
Muse Istago is a supportive, vision-based spirit. His major ability functions as Major Image (improving to other spells as you continue to level), and the fact that you can use this every five rounds means you can get a lot of use out of that. The Capstone bumps this up, allowing them to last until your pact ends.
The minor abilities include a scrying effect to peek on the dreams of others, an insight bonus on Craft (Painting), Perception (Handy!), and Sense Motive, a bonus on resisting Gaze Attacks, and a scaling enhancement bonus to ability scores with a decent number of uses. This won't stack with common belts or headbands, but it's got the potential to raise the Save DC's of abilities you want to land, help allies accomplish important tasks, and generally make your party better at doing things.
N'alyia - Vampiric
N'alyia is a vampiric spirit, with a major ability that can deal a moderate amount of damage to foes and provide temporary HP for either one hour or until the pact ends. Note that the damage dealt to creatures is untyped - so it'll go through most defenses - but you'll have to think carefully about how you want to use it. Front-line characters may not want to use such an ability during battle, while rear-line characters will probably want to avoid doing melee touches in the first place.
(You could, however, siphon HP from an ally before you're expecting a fight, and then heal them somehow - a simple Wand of CLW would work for that, or binding a healing spirit like Ubro. This padding of HP could be quite helpful for any character likely to be taking damage.)
N'alyia's minor abilities continue her vampire theme, and include uses Charm/Dominate Person, transforming into a bat (flying!), bonuses on Fly and Stealth, and a melee touch attack you can do as an extra during a full attack that can meaningfully reduce the opponent's Constitution score about 75% of the time they fail their save. If you don't plan to make full attacks, you can get a Dire Bat as a companion instead. Overall, N'alyia is definitely better for people who get up close and personal with their foes, but the transformation and flight are decent utility for any character.
Nivea Nieces, The - Poison/Mind or Poison/Defense
The Nivea Nieces are one of the more complicated spirits - like Cornelius Button, there are two potential spirits you can bind, but unlike him you don't have any recourse if you don't get the one you want. In fact, the way it's set up you probably won't get the spirit you want most of the time - it's actually easier to go for the one you don't want, especially because their Binding DC goes up (reducing the chances of a Capstone Empowerment and increasing the chances of a Poor pact) if you get it wrong.
Yeah, they're this complicated and we haven't even gotten to the powers yet. Anyway!
Mariath is a poison and mind-affecting spirit, with a major ability that forces the target to roll and act according to a list provided. The Capstone makes them roll twice and allows you to pick which one occurs. Her other abilities include hitting targets with hallucinations, turning an arm into a venomous snake (whose poison deals Constitution damage), and a bonus on Craft (Alchemy) and Survival.
Taydie leans heavier on the poison, with a major ability that does Wisdom damage - and, unusually, it's resisted by Will instead of Fortitude. Her minor abilities include transforming into a spider-like entity (no climb speed), a buff for using Poisons, thorny skin that discourages grappling, unarmed strikes, and natural attacks, and the same bonus to Craft (Alchemy) and Survival.
Obba, Ella, Atasha - Mind-Affecting
Don't worry, this isn't an even more complicated version of the Nivea Nieces - although you do have a randomized personality influence if you make a poor pact. This spirit is another one with a focus on mind-affecting powers, starting with a major ability that lets you take away a target's ability to speak as a melee touch attack (or within 30 feet if you get the Capstone). The obvious use here, of course, is shutting down spellcasters - although they tend to have high Will saves, so this won't work as often as you might like unless you get your Save DC's pretty high.
The minor abilities include blinding everyone within 30 feet (Fort reduces to 1 round, but can't entirely stop it), casting Love Spell, no penalty if you're trying to deal nonlethal damage, and use of a Suggestion effect. They're not very good as a battle or social spirit, but that blinding effect can create a strong opening for the rest of a party.
Sybee Rose - Combat
Sybee Rose is definitely a battle spirit, and offers a very nice amount of flexibility when bound. Her major ability is the use of a Fireball effect, with a Capstone dealing added damage at the start of their next turn. Remember, major abilities tend to be 1 or 2 uses per-battle, but that's a very nice effect for starting the battle with a bang... or, better, wrecking swarms.
Her minor abilities include feigning death, protection from fire, bonuses on Bluff and Diplomacy, and your choice of several good witch hexes (running off Charisma instead of Intelligence). This gets even better at higher levels, since you'll be able to get more than one hex at once. My feeling is that Sybee Rose is one of the better third-level spirits for any binder who isn't on the front lines, and the good list of hexes means she's a solid choice as a secondary spirit for quite a long time.
Tommy Greensprout - Debuffing
Tommy Greensprout is definitely one of the weirder spirits - there's a whole Prestige Class about his powers and theme. Put simply, though, he's an age-focused debuffer spirit. His major ability lets you steal the adulthood of humanoid targets - and is useless against everything else, mind you - generally reducing their physical and mental scores in accordance with a table on aging effects provided elsewhere in the book.
His minor abilities include decent bonuses on Strength and Dexterity-based checks, becoming a Youth (which improves Dexterity, but reduces Strength, Constitution, and Wisdom), use of Uncanny Dodge, bonuses to stealing, and a permanent fly speed as long as you're bound to him.
Vandrae - Debuffing/Assassination
Vandrae is a debuffer and assassin spirit. Her major power is a melee touch effect that can poison foes and put them unconscious for a round - setting them up for a Coup de Grace - and the capstone makes it so that even if they succeed on their saving throw, they'll take a -4 penalty to Perception (kinda blah in combat) and attack rolls (kinda GREAT in combat) for 4 rounds. Note that it's still not going to work on anyone immune to poison, though - they don't even need to make a saving throw in the first place.
Her minor abilities include counterspelling a decent number of times per day, use of a Deeper Darkness effect (make sure you can see!), a bonus on Perception and Stealth checks, and a minor Sneak Attack. If you're not going to be able to see in the darkness you create, you can swap that out for a scarlet spider familiar.
Overall, Vandrae is a pretty solid choice at this level - not too many foes resist poison, and between that and the counterspells, she's pretty good at shutting foes down and helping the rest of the party tear them to pieces.
Xalen d'Marek - Knowledge
Xalen d'Marek is a knowledge-based spirit. His major ability is a Reduce Person effect that works regardless of creature type - and shrinks them two sizes, no less, or one if they fail their save. The Capstone lets you target multiple creatures. You won't want to do this on any foe that wants higher Dexterity, but otherwise it's a pretty potent shutdown that will leave them more vulnerable to the rest of your party's attacks.
His minor abilities include an untyped bonus to Intelligence (with the stipulation that all new skill ranks must go into one Knowledge skill), a bonus on all Knowledge and Spellcraft checks, use of Locate Object to find written documents, and a bonus on saving throws versus certain kinds of traps. You can gain a raven familiar instead of the ability to find written things, and that's probably worth taking most of the time.
Now, aside from the major ability that may make your GM throw a book at you when he has to keep recalculating stats (using a program like Hero Lab makes it easier, I might add), Xalen's main use is clearly research... as in "researching other spirits" (or, more rarely, other subjects). Xalen's powers stack with the Pactmaker's Occult Knowledge and Revelation of Brilliance abilities, and together, these abilities will almost certainly let you power through the tasks for researching other spirits. For that reason, if you don't need any other third-level spirit right away, it's probably worth researching Xalen as soon as you can - maybe even before you can bind him - so he'll be available when you have the free time to research.
Xasa Culthic - Stealth
Xasa is something of a defensive sensory spirit. His major ability deals a great deal of sonic damage in a line (Reflex halves), with a Capstone that turns half of it to Slashing (which doesn't mean much most of the time, but could be handy if you find something weak to that). His minor abilities include controlling sounds, hiding your alignment, gaining pretty good Spell Resistance (as an immediate action, which - remember - takes your swift for the next turn), and blindsense for a short distance. The vestigal bond trades the spell resistance for a fiendish ape companion.
There's a lot of potential here if you're creative - the spell resistance alone is a good effect for anyone who gets targeted by those often (Fighters versus Mind Control, anyone?), while the sonic blast will be effective against most enemies. Overall, a solid choice in combat with some decent utility outside of it.
Level 4 Spirits
Anajira - Skirmishing
Anajira is built around skirmishing - as exemplified in his major ability, which lets you move up to your speed and perform a standard action during that move. It is, essentially, a Flyby Attack. The Capstone lets you avoid provoking AoO's for movmeent (but not other things). His minor abilities include a melee (or ranged) touch attack that deals untyped damage, a transformation that gives you two claw attacks and a fair number of skill buffs, a scaling enhancement bonus to Dexterity and Charisma, and additional attacks with either the untyped damage or the claws when making full attacks. You can trade the extra attacks for a Panther, functioning as a mount and with abilities as a Druid's companion.
Anajira's definitely one of the more limited spirits, and while the skill bonuses aren't bad, they're not something to pick this spirit for. The two claws aren't enough for a proper natural attack sequence, either - you'd probably want to get some other attacks as well... although you might get some interesting combos with other movement-based spirits, and that's probably where Anajira's real usefulness lies.
Catha of Codex - Language
Catha of Codex is a language-based spirit. Their major ability allows you to learn the truename of a given creature or object, and you're treated as having a higher binder level and better DC's against them - and this applies to all of your granted abilities, including those from other spirits. This is helpful if you have something else you're trying to land. Catha's minor abilities include at-will Comprehend Languages, a bonus on Linguistics checks (and two bonus languages), a Magic Circle Against X usable on one foe, and moderate use of the Words of Power system. The overall Wordcasting system isn't that great, but your flexibility here means you could definitely pick up some useful powers for the day. If you're not interested in wordcasting - or your GM just doesn't allow it, which is entirely possible - you can swap that for a dog companion.
Ethaniel Midnight - Debuffing
Ethaniel Midnight is primarily a debuffer, with a major ability that lets you reduce the target's Strength and Dexterity by a very respectable amount. Even if they succeed on a Fortitude Save, they still take a -2 penalty... though it is mind-affecting, so don't plan to use it on undead. His minor abilities include crafting crystallized pain, protection from others scanning your alignment, conjuring manacles around a target, a bonus to Sense Motive, and use of Discern Lies and Confess as SLA's. That said, you'll probably want to be playing in an evil campaign if you want to make the most of him...
Fey Baraddu - Polymorphing
Fey Baraddu is an animal-based polymorph spirit, with a major ability that functions like Beast Shape II and scales up later on. Interestingly, you have to stay transformed for at least five rounds once you use the major ability, because you can't dismiss it unless you use the ability again. It otherwise lasts indefinitely (i.e. as long as you're still bound to this spirit - loss of the spirit means, naturally, loss of the ability). His minor abilities include the use of Awesome Blow (excellent for knocking enemies into position), bonuses to all of your natural attacks, Wild Empathy, and Woodland Stride (both quite similar to the Druid's powers).
The major ability here offers both strong combat potential and useful out-of-combat options, so you'll almost always be able to find something useful to do... assuming you know which animals are good to turn into, of course. Like much involving Pact Spirits, knowledge tends to be your most powerful tool. (I suggest creating flash cards organized by ability, myself, so you can just flip through to something you think works for the current situation.)
Gulguthriana - Grappling
Now THAT'S a name you might have trouble repeating fast. Anyway, Gulguthriana is a grapple-based spirit, with abilities like stretching your limbs to improve your range, improved damage with unarmed strikes, and no penalty to grapple a foe without becoming grappled yourself. What you DON'T get is the "Grab" special quality, which would let you make free grapple checks on foes with your attacks.
(Pactmakers can bind Hollow Eyes at the same time to get that Grab effect, though, in which case the gargoyle transformation gets much, much nastier. This is an important thing to remember about Pactmakers, actually - even spirits that seem limited on their own may become very potent if used in the right combination. Don't think of each spirit as wholly separate - think about how they can be used together, too.)
Hexus - Curse/Survival
Hexus is a little hard to pin down into a short phrase, but... essentially, they're an animal-manipulating, curse-using survival spirit. The major ability lets you possess an animal (which you may be able to get from another pact, by the way), and the Capstone lets you possess a humanoid corpse instead. Both of these are hard to use consistently, though, so you'll want to have your own receptacles. You also make animals nervous, get a curse you can attempt on each foe once a day, use of Command Undead (with Channel Energy uses for that purpose only), and the ability to act normally when using the Diehard feat you get without taking hit point damage. Done right, all of this together can make you quite hard for foes to bring down, though you may get the best results if you sneak in as an animal, curse foes before the fight, and then bust in with your party.
Jehotek - Anti-Evil
Jehotek is a spirit based around punishing evil opponents. The major ability is a 20-foot column of "holy fire" that deals untyped damage to all targets, with a Reflex Save for half. The Capstone lets you exclude targets from this effect, as well as heal some damage... although this ability is a little unclear in its writing. Minor abilities include purifying food and water, creating blessed foods (for a Bless buff) or holy water, improved save DCs against evil creatures, use of Prayer as a spell-like ability, and inflicting Frightened on foes. Unusually, mindless living creatures and undead are NOT immune to this. You can swap the Prayer effect for a Harbinger Archon familiar.
Kami Onmyoji - Defense/Healing
Kami Onmyoji is a guardian spirit. His major ability allows you to Bull Rush enemies away from you, and the Capstone allows you to move with your target (implying, of course, that the normal version lets you toss enemies away without leaving your square). His minor abilities include Divination (as the spell), a bonus against effects that suppress or exorcise spirits (this will rarely matter), a scaling Fast Healing ability (beginning at 28 points of healing/day at 7th level), and a scaling bonus to AC and Saving Throws. Note that these powers stack with Marat's defenses if you want to go full-throttle on defending yourself.
Kandisha - Mummy
Kandisha is a mummy-themed spirit most suitable for combat, with a major ability that lets you set a permanent curse on targets. The capstone makes male enemies more likely to fail their saving throw, and the selection of curses is decent enough to be useful against most foes... although the fact you can only target humanoids makes this less useful than you might think at first.
The minor abilities include the ability to speak with birds, a constant protection from evil effect (but only against male humanoids, monstrous humanoids, and outsiders), the ability to create a sandy version of Solid Fog, and proficiency with the scimitar. The not-so-useful protection effect can be swapped out for an Earth Elemental familiar, and if you can do that, you probably should - Kandisha's a little too limited for general use, and needs the help.
Loh'moi - Space Manipulation
Loh'moi is a spirit focused on the manipulation of space. His major ability is a perfectly accurate ray of force (1d6/2 levels, as long as the foe doesn't have total cover or total concealment), with a bonus Dimensional Anchor effect if you get the Capstone. That's not necessary too often, but it's good for trying to stop teleporters from escaping.
His minor abilities include bonuses to Escape Artist and squeezing through spaces, a constant Rope Trick effect, the ability to teleport repeatedly during a full attack, and a more casual teleport for move actions and double moves. You can also swap the teleport-during-attacks for a limited Eidolon, which can still be pretty darn powerful. I don't mean in terms of attacking, either - summoning up a creature with the right skills for a day's job is also helpful, though your GM may restrict you to one specific Eidolon instead. (Either way, try to have the stats you want already written down and ready to go so you don't have to create it at the table.)
Night Fang - Battlefield Control/Tripping
Night Fang is a spirit built around battlefield control and tripping foes. His major ability allows for a Hypnotism effect that fascinates foes and lets your allies get into his position, while his minor abilities provide bonuses to Fly, Perception, and Stealth, the ability to hold your breath better, a natural armor bonus to AC, use of three spider-based spells (spider climb, web, and whip of spiders), scent, and two Trip-based feats that'll work well with the spider whip. The Vestigal Bond is unusually flexible, allowing you to swap out any of your minor abilities for a differently-themed animal companion.
Prime Ravager - Countering/Anti-Undead
The Prime Ravager is a countering and anti-undead spirit. His major ability allows you to shut down supernatural abilities you've identified, with a Capstone that maximizes the time they can't use it. The minor abilities include free movement when you make a reflex save, a pretty big bonus to your Will saving throws, free use of a Disrupt Undead effect (with bonus damage - mind you, it's still not very high compared to physical attacks, though it'll do well against incorporeals), freely disintegrating corporeal corpses, and a constant ability to see pact spirits.
The Vestigal Bond replaces all of the granted abilities, and allows you to have the Prime Ravager possess a helpless humanoid. This may be more useful than his other abilities, honestly, all of which are a bit too niche to be consistently desirable.
Son of Dobb - Roguelike
Son of Dobb is a rogue-ish spirit. Unlike most spirits, he has two major abilities (and yes, they have separate cooldowns) - one allows you to meld into stone and move around, while the other effectively gives you a mythic surge every five rounds. His minor abilities include detecting insectoid creatures (rarely relevant), an insight bonus on Sense Motive (good for social situations) and Knowledge checks to interpret dreams and prophecies (almost never relevant), as well as a bonus to Disable Device and UMD, plus disarming magical traps. The Vestigal Bond is worth considering - if a creature would die, once (or more times) per day you can cast Breath of Life as an immediate action and teleport them to a safe area. This is good for PCs and even better for NPCs you need to keep alive. You will, however, randomly lose one of Son of Dobb's major abilities.
Swan Elashni - Mind-Affecting
Swan Elashni focuses on mind-affecting abilities, mostly in a supportive role. The major ability dazes foes and improves the target's attitude towards you (no saving throw!), and the Capstone somewhat expands the list of targets you can affect (although it will rarely be relevant). The minor abilities include a Calm Emotions effect, walking across water, a bonus to Perform (Dance), and a bardic performance you can use on yourself for a relatively small buff.
That said, Swan Elashni is not a particularly powerful spirit - none of their powers are real stand-outs, though the major ability is quite useful if you want to have a better chance of swaying someone to your side.
Vaukner - Paladin Powers
Vaukner is a reflection of the Paladin class, with the same focus on protecting allies. The major ability provides all allies within 10 feet with a small amount of temporary HP (honestly not that much, though the capstone adds more), while the minor abilities include an aura of courage, improved use of the Intimidate skill, minor healing when you strike a foe with an opposing alignment, and the ability to transform weapons into axes. Like Swan Elashni, none of these are overly powerful abilities, making Vaukner a secondary choice unless you really need that resistance to fear.
Level 5 Spirits
Arthu - Martial
King Arth- I mean, Arthu is a combat spirit. His major ability allows each successful attack you make in a round to deal 3d6 (or more) additional damage - naturally, this is most helpful if you make and can land a lot of attacks. The Capstone adds a free trip attempt when you make a full attack, which you'll probably want to use whenever you can to maximize the damage you can do. Minor abilities include the summoning of a Dancing Longsword that can attack for you, a bonus on Diplomacy and Knowledge (Nobility), a morale bonus that's similar to Swan Elashni's but affects your allies (making it mechanically much better), and the ability to send a message to a creature within five miles of you once an hour. If you don't want the dancing blade, you can swap it for a faerie dragon familiar.
In all honesty, Arthu isn't that great all on his own - the extra 10.5+ damage per hit (average) with his major ability is nice, and the buff to all allies is welcome but probably outclassed by almost anything a cleric or other dedicated buffer is doing at the levels when this spirit first becomes available. Combined with another battle spirit, though, he could end up quite a bit more dangerous.
Beautiful Balr - Tanking/Supporting
Balde- I mean, Beautiful Balr (who is definitely not a certain famous norse deity, we swear) is a defensive spirit, with a side of supporting. His major ability allows you to flat-out deny an attack that an opponent makes (although it's not effective on things without attack rolls - like swarm attacks - or any spell not affected by Spell Resistance). Note that this only works on one attack, and after that it's expended for five rounds.
His minor abilities include challenging a foe so they can only attack you, feinting as a move action (or a swift action if you have Improved Feint), doubling all morale bonuses on one ally, and a bonus to Charisma checks and skills.
Naturally, Beautiful Balr is most appropriate for a party member acting as a Tank - it's hard to overstate the value of literally forcing a foe to focus on you and then smacking an attack of theirs away. He's also a decent backup for a character who really needs the protection... and doubling the morale bonuses on a character is flat-out great if you happen to have a Barbarian or Bloodrager on your team. It only lasts until the end of the turn, but that can be a pretty sizable boost for them. However, note that Beautiful Balr is a little Swift/Immediate heavy - if you use one of his powers, you may not find it so easy to use the others.
Circe's Runes - Utility Casting
Are you noticing a lot of real-world influence at this level? Because I am. Circe's Runes are something of a utility spirit - and they're terrible as a primary spirit, but decent as a secondary choice. Their major ability lets you change one spirit out for another as a full-round action, which is useless for non-Pactmakers and basically an emergency measure if you really, really, really need to change. (If you do, it's probably to get a healing spirit or something.)
Her minor abilities include a bonus to Know Arcana, Spellcraft, and UMD, striking enemies with a Moonstruck effect, performing a divination (i.e. asking the GM) about which spirits will be most useful in the next day, and the selection of one or more runes that give spell-like abilities. There are a TON of options here - for this power alone, Circe's Runes are probably the most flexible spirit you can get, and the spells can support almost any playstyle you want. Shore up a weakness, perform your main role better... they all get a decent number of uses, so look over the list and figure out which rune seems like the most helpful to you.
Dark Blood - Generalist
Dark Blood is a generalist spirit, and a pretty good choice if you're not sure what you'll be doing in a day (or expect to face a variety of situations). His major granted ability is quite the curious one - as a swift action (or a free action with the capstone), you can get an extra standard action - but you lose your standard action in the next turn. This has a nice synergy with Tyrant Cromwell, who gives you access to the Vital Strike line and can help you maximize the power of that extra action.
Dark Blood's other abilities include disguising your granted abilities (helpful if you don't want to be obvious about what you're doing), a self-polymorph giving you a variety of bonuses for combat, the ability to detect the thoughts of others, and bonuses to all of the social skills.
Green Glomairah - Tanking
Green Glomairah is a defensive nature spirit. Her major ability allows you to throw off a variety of negative effects from affecting you for a turn, which is helpful for getting the chance to cure them without being hampered.
Her minor abilities include casting spells from the Plant domain, immunity to disease, poison, emotion, fear, and morale effects, speaking with plants, and a Tree Stride power. You can trade the domain spells for a treant companion.
As you might expect, there are essentially two situations where she's truly useful. First, if you're expecting to deal with a bunch of plants in a day, she's a pretty potent choice. Alternatively, if you know you're going to be facing a lot of negative effects, she can ward those off. The use of domain spells is handy, but not a reason to bind this spirit all by itself unless you're moving through a plant-heavy region.
Loathix - Combat
Loathix is a weather-controlling combat spirit. His major ability deals significant sonic damage in a long line, with a capstone offering the chance to permanently deafen them. Minor abilities include cursing someone who slays you - with a chance to revive you in the process - as well as immunity to a variety of effects (this stacks well with Green Gloamairah if you want to tank through conditions, by the way), the ability to increase the recharge of the major ability to trip foes, and use of a Call Lightning/Control Wind effect.
Overall, Loathix is a pretty solid spirit - the death curse won't come into play very often, but the other abilities are solid combat choices and warrior types in particular will probably get a lot of mileage here.
Mishpo - Thievery
Mishpo is a thief-oriented spirit. His major ability is a Freedom of Movement effect that also lets you go through wood, stone, metal, and lead as if you were incorporeal - though solid sheets of lead still block you. If you hit the capstone, you don't provoke attacks of opportunity when you move - but either way, it's a pretty handy ability for getting where you want to be.
His minor abilities include bonuses to Bluff and Sleight of Hand (with an added bonus when using it to generate GP or capital), your choice of up to three spell-like abilities, the ability to disarm traps (or set them as a ranger), and a big bonus to Bluff or Intimidate as a swift action. You can trade the spells for a different set, plus the use of the Ranged Legerdemain ability of the Arcane Trickster.
Noble Marius - Grappling
Noble Marius is a grapple-based spirit, with his major ability allowing you to affect grappled foes with a Feeblemind effect. With the capstone, even a successful save gives them a -4 penalty to their mental ability scores, reducing the power of their spells (and will saves!) for a full day.
His minor abilities include bonuses to Bluff, Disguise, and Knowledge (Nobility), a Clairvoyance/Clairaudience effect that can look into the past, extensive use of Telekinesis as a spell-like ability, and several bonuses that make grappling attempts practical for you. You can swap the Telekinesis effect for a Telepathic Bond.
Honestly, being able to drain a foe's scores (or hit them with Feeblemind) is the real purpose of this spirit, but if you have time and need information, the ability to look into the past is a nice utility effect. Noble Marius isn't the first spirit of this level I'd research, but he's probably worth getting at some point just so you have that utility option if you need it.
Omlan Atlan - Downtime
Omlan Atlan is a kind of downtime spirit, with a particular focus on helping out the rest of your adventuring party. His major ability lets you create a duplicate of yourself (as lesser simulacrum), while his minor abilities cover bonuses to arcane spellcasters making concentration checks (Wizard near enemies? Help them cast!), use of the Fabricate spell, bonuses to Knowledge Checks (with a list that can help you with three of the research tasks for getting a new spirit - Xalen d'Marek is still better for that, but if you want to use Omlan's other abilities, he's a good secondary choice for that), and the ability to accelerate a target's retraining efforts.
None of these abilities are particularly good for adventuring days - except the bonus to concentration checks, anyway. In that sense, a lot of Omlan Atlan's usefulness is determined by the amount of downtime your campaign has. If you have a lot of downtime, then he can help you research spirits and create items to sell or use - and let your party members retrain options they don't like. On the other hand, if downtime isn't a thing in your game, he's largely useless.
Pavatu - Generalist
Pavatu is a general-purpose spirit with a wind-based theme, and a pretty good choice for a primary spirit once you hit this level. His major ability lets you change your normal and touch AC until the end of your turn, and the capstone lets you give the result and protect an ally. His other abilities include reducing falling damage (almost never relevant), a scaling transformation into an air elemental, use of the Sending spell a high number of times per day, benefits of two movement-based feats, and a decent number of uses for becoming invisible for a short time. All in all, Pavatu's a fairly solid spirit - not much in the way of added damage unless the transformation is a powerup, but you do get quite a bit of flexibility.
Rattenkönig - Exploration
This spirit is another adventuring spirit, although its usefulness can vary quite a lot based on your foes. The main ability allows you to turn into a swarm of rats - and if your enemies don't have AoE attacks, well, they're pretty much screwed. The minor abilities include a bonus against effects causing Sickened or Nauseated (which might come into play if you're going through sewers), the ability to essentially consume the corpse of a creature of your type and get a stat bonus from it, use of Darkvision and Scent (with added ranges if you already have these powers), and the Solo Tactics power of the Inquisitor.
The strength of this spirit is also its weakness - if your opponent has strong AoE powers, you're not going to get much out of this spirit. I mean, don't get me wrong, that stat bonus from dead foes is nice - but it's not something you can always rely on, and it's certainly not worth a bound spirit slot all by itself. In that sense, you may want to perform divinations - say, via Circe's Runes? - before binding this spirit.
Tentacles of Dagon - Aquatic
Oh, the jokes I could make about this spirit. Dagon is another aquatic spirit, and it's probably worth looking into binding some of the other aquatic spirits at the same time. His main ability allows you to delay harm to yourself, although it's worth noting that damage-reducing effects are applied before using the power. It would, however, give you an opportunity to heal up before taking the damage - handy if somebody scored a critical.
The minor abilities include transforming into an anthropomorphic kraken (for minutes per-day, so mostly combat-only), bonuses to swimming and the ability to breathe water (all day!), use of a divination power that gets better if you're one of Dagon's allies and worse if you're one of his enemies (and you probably will be, because he doesn't like humanoids), and bonuses to Knowledge and Sense Motive checks. Interestingly, this makes him pretty good for doing spirit research at the same time you're having underwater adventures.
Teu and Lae - Movement
This is another double spirit, although swapping between the two is pretty easy if you hit the Capstone. Teu's major ability allows you to swap places with a foe that's within 60 feet, potentially putting them into a grapple - although they get a Will Save, this can be an interesting way to catch and subdue a target. Lae's major ability lets you teleport up to thirty feet, with the chance to cast Chains of Perdition as a swift action.
The minor abilities are mostly shared. These include use of the Paladin's Lay on Hands (at half your level for strength, and with a number of uses equaling your Charisma modifier), a pounce-like effect whenever you use the major ability, all-day use of a Tongues effect (handy utility!), and either a bonus to Initiative and Reflex saves or Beast Shape III (canines only) at-will, depending on which one you're bound to.
Teu and Lae work best when your whole party is willing to cooperate with them.
For example, they could grapple you first (through the bars of a cage you
brought?), and then you could teleport out of that grapple and make a full
attack against a minion back where the enemy was before you moved... although
you'll want defenses of your own if you get out of formation that way. There's
also a decent chance foes will avoid that power, though, so it shouldn't be
totally relied upon. In that sense, Teu and Lae work best as a secondary
strategy.
I'd definitely learn this spirit if possible, though. All-day Tongues is handy if you're worried about communicating with locals, and the other minor abilities aren't too shabby.
Triteia - Aquatic
The Little Merm- Ahem, Triteia is another aquatic spirit - and while I hesitate slightly about the imagery of putting a mermaid princess and the tentacles of a demon lord together, they actually are a rather solid pair for underwater adventures. (Non-Pactmakers, who can only bind one spirit, may find themselves a bit more limited.) Her major power is a blast of sonic damage (i.e. works on almost everything) doing 1d6/level, with a Fort save for half and a Capstone that adds a stunned effect. The bad news is that it's a 30-foot radius and hits everything, so your allies shouldn't be too close to you.
Triteia's minor abilities include multiple uses of the Merfolk Transformation spell, which is new to Pact Magic and good for letting the rest of your party go underwater. (Also, because it's Permanent, have a way to dispel it when you need to breathe air again.) Other minor abilities include multiple castings of spells from the Water Domain and Aquatic Bloodline as SLA's (i.e. no components), and the ability to speak with aquatic creatures.
The Vestigal Bond here is interesting, and makes her worth learning even if you don't plan to go underwater - essentially, you can transform into a specific humanoid of a particular race, which can be really, really good for blending in with locals.
Vodavox - Generalist
Vodavox is a general-purpose spirit with an emphasis on mental things. His major ability is a cone-shaped blast dealing 1d6 untyped damage per level, but as a mind-affecting power it's less useful against undead. With the Capstone, anyone taking damage has a chance of becoming Dazed as well, which is a handy add-on.
His minor abilities include resistance to mind-affecting powers (which is VERY good if you have a low Will Save... Fighters, I'm looking at you), bonuses to Escape Artist (eh) and Perception (great!), a tripling of your Carrying Capacity, a transformation into an insect that has one natural attack and spell resistance, and use of Telepathic Bond as a spell-like ability.
Overall, Vodavox is a spirit that will work best with a martial character who can really use the benefits he offers. Pactmakers have better spirits for offense and good Will saves to begin with, and the bonus to carrying capacity is best for characters that are quite strong to begin with.
Level 6 Spirits
Before we get into these, there's an important thing to remember - this level is where some Binders cap out. Stronger binder classes can go all the way to 9th-level spirits, but those who are operating more as amateur binders are limited to this.
Alrik of Malkeborne - Combat
Alrik is a combat-focused spirit. His major ability is a standard action that deals an extra 1d6 damage/2 levels. Note that since this is described as its own action, it does not stack with special attacks like Vital Strike... but other bonuses (like Sneak Attack) may be able to apply. His minor abilities include sickening all creatures that get within 10 feet of you (including allies - although you can ditch this for the Vestigal Bond), proficiency with the Bastard Sword (and a free Anarchic effect), reduced penalties for wearing medium armor, and bonuses to Heal and Know (Nature).
Damian Darkstar - Generalist
Damian Darkstar is a general-purpose spirit - and definitely has the chance to be one of the better 6th-level spirits if you can bind him. His major ability can cause 3d6 points of (untyped) damage with no save, and a pretty nasty suffocation effect. As if that wasn't enough, the zone created also dampens sound, blocking sonic effects (admittedly rare) and silencing foes (more useful). Characters that rely on spells and have low Fortitude saves - like, say, enemy wizards - aren't going to enjoy this. The capstone lets you move the zone you create.
Damian's minor abilities include a constant Life Bubble effect that wards off planar hazards, quite a few uses of the Reverse Gravity spell, 60 feet of perfect flight (with interstellar travel), and at-will levitate/hostile levitation within 20 feet. Overall, that's a nice set of abilities, most of which are likely to be quite useful on any given adventuring day - although it is important to have ranged abilities if you plan to fly above your foes all the time.
Death Howls - Anti-Incorporeal
Death Howls is an Ethereal-based spirit. His major ability is effectively an anti-Incorporeal ability, giving your weapon the Ghost Touch property until the end of the turn. If you're fighting a corporeal target, you can target Touch AC instead - nice, but since most people using this spirit will be damage dealers, this won't actually make much of a difference most of the time. The Capstone gives you a bit of added damage.
His minor abilities include regular use of a See Invisibility power, points you can spend to use Blink (or, later, Ethereal Jaunt), Endure Elements versus cold, and the ability to give allies rerolls with a +2 bonus as an immediate action.
The rerolls are pretty useful - saving teammates from failed saving throws, anyone? - but otherwise, this spirit probably isn't the best choice unless you expect to be fighting a lot of incorporeal foes. Most damage dealing characters will get more use out of a different spirit instead.
Demos Kalagos - Time
Demos Kalagos is a time-manipulating spirit. His major ability allows you to undo a target's turn - although your GM might have Opinions about all the added work - and the Capstone adds a Maze effect that can shut them down for several turns.
His minor abilities include using two Swift or Immediate actions (or one of each) in a round by 'stealing' it from the next round, bonuses on Disable Device and Sleight of Hand, creating supernatural Ranger traps, and resistance to aging, Slow, and teleportation effects. His Vestigal Bond lets you trade the extra quick actions for multiple uses of Haste or Slow, as well as Alter Age and Time Stop at high levels. This trade is worth making unless you're really reliant on swift actions - you'll probably have at least 9-10 uses a day by the time you get this spirit, and that's easily enough to give your whole party Haste in every battle. (Characters with low Charisma scores won't find this quite as useful, but Haste is still a good buff to have)
Everrona - Battlefield Control/Debuffs
Everrona is an age-themed spirit, with a particular focus on debuffs and battlefield control. Her major ability allows you to bestow negative levels on anything susceptible to aging, with the Capstone significantly increasing the average you'll get from foes. Note that they do get a Will save, so this isn't a totally consistent power.
Her minor abilities include casting Greater Flames of Youth (a new spell from Pact Magic that can reduce a target's age by two ranks, meaning some pretty hefty ability score penalties), Plant Growth and Diminish Plants as at-will spells, use of Imprisonment a decent number of times per day, and a constant youthful appearance that lets you talk with children.
Everrona has the potential to really mess with enemies... but only if your abilities are successful. For that reason, she's best when used by someone who has high Save DC's - more martial characters won't find her quite as helpful, though the permanent youthful appearance has some interesting utility if you need to sneak around.
Hy'Ryia - Life/Flexibility
Hy'Ryia is a life-based spirit, with power manifesting in several different ways. Their major ability allows for the use of Telekinesis or Telekinetic Charge (chosen when you use it), with a capstone allowing you to do either as a swift action (albeit at a longer cooldown).
The minor abilities include reincarnating slain animals and humanoids (although there's a 24-hour delay, so don't expect quick and easy revives in dungeons - and it doesn't apply to native outsiders like tieflings), at-will use of mage hand, giving weapons the Dancing property, and harming yourself in order to heal others. It's not a huge amount, and it's once per day per target, but it's something.
However, the really sneaky thing here is Hy'Ryia's last minor ability, Unity in All Things. This lets you get any one minor granted ability from a 5th Level or lower Starless Spirit. Triteia's Water domain spells? Yup. Kami Onmyoji's Repair the Ward? You betcha (and it's got good synergy with Hy'Ryia's power to heal others).Anajira's enhancement bonus to Dexterity and Charisma? Sure.
Flexibility is the real strength of a binder, and a power this open-ended could be a huge benefit to your playstyle - or something that shores up a weakness. Even better, Hy'Ryia's status as a Starless spirit means that pretty much any binder can access it, including those limited by the Tunneled Lore class feature. As such, Hy'Ryia is definitely worth researching - maybe not as the first 6th-level spirit you go for, but almost certainly as the second.
Jayna Warlock - Elemental
Jayna Warlock is an elemental-based spirit. When bound, you select one of seven elements - air, earth, fire, metal, void, water, and wood. (This probably sounds familiar to those who like Kineticists...) Your choice for that determines the rest of this spirit's abilities.
Jayna's major ability includes casting any 4th-level or lower spells from the associated spell list of the elementalist wizard, with the cap increasing to 5th-level spells at 14th level (not so far away by the time you can access this spirit), and capping at 6th-level spells when you hit Level 17. Some spells have reduced durations, but aside from the cooldowns, you've basically got unlimited use of those spells. The capstone allows you to Empower them three times per-day.
Jayna's minor abilities include dealing damage to foes with varying elements, using an associated Wall spell, and gaining energy resistance or DR based on your element. Now, here's where the hard choice comes in. Broadly speaking, the more useful your attack element is, the less useful your defense is going to be. Void's ability to hit foes for sonic damage will be pretty reliable, but honestly, how many enemies are going to throw sonic attacks against you? Similarly, if you're wanting to resist fire damage as protection, how likely do you think it is that throwing fire at your target will do much?
Defenses tend to be easier to get than attacks, so you may want to focus on the offensive powers of this spirit and just toughen up another way. That said, don't forget the utility here - even a small amount of energy resistance can protect you from a lot of environmental effects. You probably won't need that every day, it's worth keeping the option in mind.
Loresir Claw - Damage
Loresir Claw is a damage-dealing spirit, and pretty reliably so at that. His major ability allows you to shoot rays of fire that deal 1d6 points of fire damage per binder level, though you can't target the same creature with both blasts. If your foe is resistant to fire, you can also unleash a sonic boom (2d6 + binder level in sonic damage) every round, or you could use the natural attacks this spirit bestows. Notably, the natural attacks get stronger if you already have them, which offers some interesting synergy with spirits like Fey Baraddu.
The other two minor abilities include a breath attack that can confuse foes and the ability to avoid having the extraplanar subtype. Obviously, this only matters if you're traveling beyond your home plane, but it provides essentially blanket immunity to spells that could throw you all the way back to your home. Definitely a rare problem, but nasty if it gets through to you.
Ma'Zad and Aza'Mi - Battle
Now here's an interesting spirit. These two are conjoined together, but you can only acquire one of them for the simple reason that they manifest based on the caller's gender - Ma'Zad for males and Aza'Mi for females. Don't expect disguises or polymorph effects to help you, either. (It follows that characters without gender - or with a gender not falling into this binary pattern, like you might see in a 3+ gendered species - may not be able to summon this spirit at all, but that does seem a bit harsh. If you're in this situation, I recommend talking to your GM and picking one of the two spirits.)
Ma'Zad is definitely a battle-based spirit, with his major ability allowing you to trip and push foes away. The capstone allows you to rip items away from the target (including, potentially, important gear they have!), which could be pretty handy against a gear-reliant foe. His minor abilities include an untyped bonus to your Dexterity, use of Combat Reflexes (or a bigger bonus to your Dex if you have the feat), the creation of an ice dagger with variable property, darkvision, at-will Produce Flame, and free counterattacks against the first foe to target you every round. Overall, he's quite a solid choice for martial characters.
Aza'Mi is also a battle spirit, but a bit more strength-based (versus Ma'Zad's Dexterity focus). His major ability allows you to attack every foe within 30 feet, which is handy against large groups of weak foes and less so at other times. His minor abilities include a Strength bonus, Power Attack (or a bigger strength bonus), darkvision and at-will Produce Flame, poisoning your weapon as a move action, and the ability to conjure thorny armor for yourself. This won't stack with armor you're wearing, but you do get a +9 Armor Bonus to AC and DR 5/Adamantine, which isn't too shabby for anyone, and the thorns on the armor act as armor spikes. Note that you're not actually wearing armor here, so you aren't at risk of Arcane Spell Failure if you use this ability.
Merickel - Generalist
Merickel is something of a general-purpose spirit with a lean towards combat. His major ability allows you to steal a target's destiny - or rather, a d20 roll they made. Once you have it, you can use that yourself in place of another roll. Note, however, that you can only have one roll stored at a time and the ability won't even start cooling down until after you use it - so rather than 'banking' a good roll, you might be better off using it as quickly as you can.
His minor abilities include at-will Banishment of foes (albeit only one use per day on any given foe), plenty of uses of Freedom of Movement, proficiency with Shortbows, Longbows, and Greatswords, and the ability to summon an evil outsider bane greatsword with a scaling enhancement bonus.
Minezon - Combat (high Con)
Minezon is a combat-focused spirit, but he's really only suitable for characters with high Constitution modifiers. This is because most of his powers run off of a 'Blood Pool' whose points are determined by your Con Mod - and a spirit whose abilities can't be used isn't very helpful.
Minezon's major ability allows you to reduce all damage you take during a turn by half (applied after DR, Energy Resistance, etc.), and to shorten the cooldown by spending blood points. His minor abilities include spending blood points to heal (4d8 + binder level), at-will use of Detect Pact Spirits (not very helpful) and Status (somewhat more so), avoiding attacks of opportunity that you'd normally provoke when trying to grapple foes (plus hitting them to regain blood points - VERY important for using this spirit, and great synergy with Gulguthriana), and a bonus to Strength and Dexterity (or a bonus to your Save DCs) that makes grappling foes even easier.
Primordial Titans - Combat
The Primordial Titans are another combat-focused spirit - there's a lot of those at this level - and they're definitely most effective if you're using them on a Full BAB character (or at least a heavily combat-oriented Pactmaker), rather than a less-accurate class.
The major ability here is a shout that confuses all targets in a 40-foot cone. If you hit the capstone, you can also target a 60-foot line or a 20-foot burst to help you avoid your enemies. Their minor abilities include proficiency with all armor, a reduced Armor Check Penalty, use of Blade Barrier as a SLA, proficiency with Greatswords and Greataxes, improved damage with two-handed weapons (as a Lead Blades spell), and insight bonuses to your Know (History), Know (Planes), and Know (Religion) checks. Together, those three skills cover all four categories for researching spirits, making the Primordial Titans quite useful if you want to research during an adventuring day.
Note that the skill bonuses do not stack with Xalen d'Marek's (who is easier to bind and still slightly better at research thanks to his Int bonus), so don't think about binding both of these spirits in order to research more effectively. ...Of course, at this level, you're probably not having much of a problem with that anyway.
Rasputin - Debuffing/Trickery
Contrary to what you might think, this has absolutely nothing to do with a certain historical figure who appeared in a frosty Adventure Path from Paizo. This Rasputin is the Bleeding Ringmaster (and rival of Demos Kalagos), and he's pretty nasty overall - as might be expected from what's basically a carnival host.
Rasputin's major ability, Freakish Touch, allows you to inflict a permanent deformity on a target, which gives them a -4 penalty on many Charisma checks and twists them in very uncomfortable ways. The Dogfaced deformity, for example, gives a big penalty to attack rolls, saving throws, skill checks, and ability checks - witches might be a bit jealous, but then again, they can use their Evil Eye from further away than a touch. The Face Wipe deformity, on the other hand, renders the target blinded and deafened, and it even applies to blindsense, blindsight, keen scent, and scent. These deformities are brutal handicaps, and foes who suffer them probably aren't going to last much longer.
Rasputin's minor abilities include short-range teleportation to throw foes off, use of Sleight of Hand in place of your normal AC, a good bonus on Acrobatics, Escape Artist, and Sleight of Hand (plus always getting to Take 10), and decent use of whips. All-in-all, the kind of spirit that will make your foes have a very bad time.
Serapith - Generalist
Don't let the name and Angel constellation fool you - Serapith is a neutral-aligned spirit for a reason, but you do get a lot of angelic powers to use.
His major ability is a ray of light that deals 2d6 points of untyped damage per binder level, and by the time you even get this spirit, you're probably hitting with ranged touch attacks basically all the time. A successful save reduces the damage to 5d6. The capstone gives humanoids a -2 penalty on their save against this ability. But let's face it, as far as attacks go, this one is pretty brutal.
Serapith's minor abilities include a 60-foot perfect fly speed for basically the whole adventuring day, deflection bonuses to AC and resistance bonuses to saving throws (probably not stacking with common gear, mind you), multiple uses of a Smite effect against humanoids, and a burst of light that can blind foes, affect them as a daylight spell, and dispel magical darkness effects of a level equal to or lower than your maximum spirit level (which, at the level you can get him, is basically all of them). You can also trade the wings for a Cassian Angel familiar.
Level 7 Spirits
This is the point at which spirit options really start to narrow - Pactmakers will forge happily onwards, of course, but some archetypes that offer binding don't allow spirits from this point on. Be sure you know the limits of your character when planning which spirits you want to get.
Bercilak Hautdesert - Mitigation/Recovery
Bercilak Hautdesert is a defensive spirit, but not as directly as those that raise your AC and/or saving throws. Rather, he's more about mitigating effects and recovering afterwards.
His major ability allows you to curse a target (with the capstone making it permanent), causing them to lose all weapon and armor proficiencies and increasing their spell failure chance by 25%. It also removes all class skills and causes them to treat all terrain as difficult terrain, which will make it much harder for them to get around.
His minor abilities include a bonus against mind-affecting powers, use of the Slippery Mind rogue talent, many uses of Regenerate (albeit only on yourself), and the ability to dominate fey and evil outsiders (unless you're 20th level, when you can target any creature). His last minor ability makes you immune to ability damage (but not ability drain) done to your physical scores, and very unusually, the ability to survive if your head is cut off. This is a rare defense against enemies with vorpal powers - which is rare enough to not normally need a defense against, but if you know you're going to face someone with it, this could make all the difference.
The Vestigal Bond allows you to swap out the domination power for better use of Aid Another, including a higher bonus and an expanded list of things you can help with.
The Crow - Generalist
The Crow is a shadow-based general spirit. His major ability allows you to use Shadow Conjuration and Shadow Evocation to duplicate instantaneous spells, with the capstone letting you use spells with durations as well.
His minor abilities include turning into a crow (per Beast Shape III), use of Two-Weapon Fighting and Weapon Finesse (with an extra effect if you already have TWF), regular uses of Mirror Image (or Greater Invisibility, at a higher cost), and a fortification effect against critical hits and sneak attacks. You also automatically stabilize if you're dropped below 0 HP, and automatically succeed on Fort saves versus massive damage.
With offense, defense, and reasonably flexible spellcasting - albeit shadows instead of 'real' spells - there's a lot to like with this spirit. It's not truly outstanding in any area, but for Dex-based characters, it covers pretty much all the bases.
Dead Kings - Commands
The Dead Kings are a spirit of rulership, with a variety of niche but useful powers. Their major ability deals 1d12 points of (untyped) damage for every 3 binder levels you have - and reduces the cooldown on expended abilities, including itself, by 1 round. That's really only useful for Pactmakers, but with an average combat in the game lasting about four rounds - with table variation, of course - this generally turns major abilities from once per fight to twice per fight, and that's a very respectable buff.
Their minor abilities include casting Geas/Quest on others (with a bonus against your own race), creating your own personal palace, a bonus on all Knowledge checks (useful for researching spirits!), and banishing creatures with a Maze-like effect. If you're not too fond of giving people orders, you can trade the Geas/Quest effect for a King Crab familiar.
The Elysium Choir - Protection
The Elysium Choir is mainly a protective spirit, but not one totally lacking in offense. The major ability is a dual-purpose power - evil creatures are affected as a Holy Word spell, while good creatures benefit from a Breath of Life power instead (with a cap on the number of times per-day they can benefit). The Capstone gives you a Resurrection effect, although - rarely for spirits - it also requires you to fork over a 10,000 GP diamond as a component, and can only be used three times a day in this way.
The minor abilities include a bonus to Perform (Sing) and Sense Motive, a Bard-like boost to attack rolls, ability checks, skill checks, and saving throws (plus a Death Ward), and plenty of uses of a Sanctuary effect and a reasonably strong sonic attack. There's some added utility with this attack - aside from not allowing a saving throw, it deals full damage to all objects, though you are capped in the number of uses per-day, so don't rely on it as your main form of offense.
Inexorus - Law
Inexorus is a law-themed combat spirit. His major ability allows you to inflict a round of bleed damage on your opponent (up to your Charisma modifier, or your Binder Level if you hit the capstone), and this is supported by a minor ability granting extra arms and the benefits of Multiweapon Fighting.
His other minor powers include the ability to add the Axiomatic property to your weapon, at-will use of Detect Chaos (with the ability to focus on specific targets), and multiple uses of spells from the Law domain that are equal to or lower than your maximum spirit level.
Jormungandr - Life/Death
Jormundandr is a spirit of life and death. His major ability allows you to average the life of two creatures. Get pummeled to low HP at the start of an encounter? Average with an enemy to bring them down and heal yourself at the same time. See an ally getting hurt? Sacrifice your own health and bring them back up. (This has some interesting possibilities for Pactmakers - if you also bind Minezon, you could grapple enemies for blood points, then spend those to heal yourself and then your allies. Out of combat, you could even punch your own allies and heal up.)
Jorm's minor abilities include automatic reincarnation if you die while bound to him, a bonus against death effects, disease and poison, electricity resistance, immunity to all of those at 20th level, multiple uses of a Cloudkill effect, and your choice of a Hydraulic Torrent, Control Water, or Vortex (whirlpool only) spell effect.
Lord Saruga - Lizardfolk Stuff
Lord Saruga is all about the lizardfolk, starting with a major ability that allows you to summon a horde of 5d6 of them for 4 rounds. You can also devour the brains of intelligent creatures to get a big boost in one skill, charm humanoids with the reptilian subtype, confuse everyone else, a big boost to your natural armor (plus darkvision and the Hold Breath ability), and the ability to outright kill and reincarnate humans (into, naturally, lizardfolk). If you don't like confusing or charming, you can get a Tyrannosaurus animal companion instead.
Mare Loviatha - Mounts
Mare Loviatha is a flexible spirit focused mainly on mounts. Her major ability allows you to petrify foes with ice instead of stone (so stone to flesh doesn't reverse it, but immunity to cold blocks it), while the capstone staggers foes even if their save is successful.
Her minor abilities include a mind-affecting power that can make foes target themselves for quite a long time, a gore attack that bypasses DR as an evil weapon, a bonus to Handle Animal and Ride checks, and the benefits of Mounted Combat and Mounted Archery. Her vestigal bond is a black unicorn companion that you can take in place of the mind-affecting power, and this may well be worth doing - at this level, high will saves are fairly common, and having a good steed will be more reliable than hoping to take a foe out of the fight.
Musha'Vadu - Shadows
Musha'Vadu is another shadow-themed spirit - and has fairly obvious synergy with the Crow. His major ability allows you to conjure a cylinder that deals negative energy damage, with a capstone that leaves a lingering Deeper Darkness effect. This isn't going to bother you, though, because one of the minor abilities also gives you darkvision and See in Darkness.
Additionally, you get multiple uses of a Shadow Conjuration effect, Shadow Walk, Shadow Step, and use of the new Siphon Sands spell, which increases the target's age category in order to reduce your own or give you a stat buff.
Portentia - Prophecies
Portentia is an oracular spirit, with abilities to match. Her major ability allows you to fuse a target's flesh, dealing ability damage to one physical and one mental score - there are separate saves for each, so you aren't out of luck if they resist the first. Each damage effect also has a rider: entangled if they take physical damage, and confused if they take mental damage. The Capstone makes things even worse by letting you target two abilities instead of one.
Portentia's other abilities include gifting creatures with a sleep that gives them a 70% accurate prophecy, a bonus to initiative, the ability to swap your initiative results with an ally's if you weren't surprised - careful reading of this notes that you can do it any time after initiative has been rolled, not necessarily right after - and the ability to become incorporeal for a decent amount of time. She also gives you a True Seeing effect, which you should be able to use for more than 10 rounds per-day by the time you get her. It's not a constant benefit, but when you want to check something specific, you'll probably have enough uses.
Quicksilver - Speed
Now you can play a superhero from Marv- I mean, a folktale hero. Quicksilver is all about speed, with a major ability focused on attack options. Each is a full-round action, but it allows you to do things like make three attacks at your full attack bonus or attack all opponents within your reach. If you have a wide reach, this gets significantly more powerful, and can outstrip some powerful spells. The capstone empowerment is especially powerful on crit builds.
Quicksilver also works well in a desert environment and can fabricate items throughout the day. However, the Quick Step is one of the really tricky things with this character. It allows you to take a 5-foot step without it counting against your movement, which is extremely good for avoiding AoO's and staying mobile on the battlefield. Don't underestimate it.
Silent Step - Ice/Monk
Silent Step is an ice/monk themed spirit. The major ability does a moderate amount of additional damage per binder level (which is a moderate damage increase, although perhaps lower than making a flurry of blows). It's most useful when you can't easily make multiple attacks, which is a little iffy.
However, the at-will ice storm can be quite a lot of damage, and getting a size category increase is very useful for monk-types. The vow of silence is also quite valuable, since it can shut down many traditional casters. Overall, this spirit works best on monk-style builds, so it's not for everyone, but it is worth considering.
Wendigo - Movement
Wendigo is a powerful movement-type spirit, with the ability to fly (as the wind walk spell) and burrow. Together, these can get you to most destinations. This is primarily useful as a secondary spirit, though, because most characters don't really need this as a focused power. However, permanent strong spell resistance is a very solid defense and worth considering in its own right.
The Iron Stomach power is more situational, but could come in handy in an intrigue-focused campaign. The Maw of Consumption is surprisingly good for utility because it can bypass hardness and damage reduction as if it were adamantine. Functionally, this can let you get through most walls and materials in the game, which goes right back to the movement-focused bit. One bite attack isn't great damage at the level Wendigo is available; this is pretty mainly for the utility.
Witch Yaba - Debuffing
Legally not Baba Yaga, Witch Yaba is a witch-flavored spirit with a very nasty main ability: inflicting negative levels. At this level of the game, the basic ability isn't overly powerful compared to, say, just doing a lot of damage. However, the capstone of 1d4 negative levels per round for up to four rounds can be a serious impediment to an enemy.
Her minor abilities include hexes, misleading foes, seeing through invisibility, and creating a shelter.
Yith'anu - Mind-Affecting
Yith'anu is a mind-affecting spirit. Its major ability allows you to paralyze a target (as the hold monster spell), while its minor abilities let you do things like improve your Diplomacy checks, inflict amnesia, swap bodies, or communicate with telepathy. This is, obviously, of limited use in an undead-heavy game. However, all of these are useful in a wide variety of situations, which makes this a solid utility choice. It may overlap with anyone focused on diplomancy, though, so those characters probably don't need this.
Level 8 Spirits
Ahnel Soltanis - Countering
Ahnel Soltanis is a slightly tricky spirit. Its major power allows you to unleash a counterattack using force damage as part of an immediate action, which is frankly kind of useful on almost any melee-focused build. This won't be as good for anyone focused on using spirits, but it's a decent choice for anyone who's only binding one spirit.
The minor abilities include access to dispel magic and knock (generally useful spells), the ability to use lesser astral projection, the ability to scan teleportation effects, and some bonuses on specific skills. Overall, not a particularly powerful spirit aside from the major ability on a melee build, and even then I wouldn't recommend this for most characters.
Doomed Salu'im - Battlefield Control
Doomed Salu'im is a control-focused spirit. Its major ability can remove a target from time for several rounds, with the potential to be permanently lost if it fails all of its will saves. If you can debuff a foe beforehand, and your save DC is high, that is extremely potent.
The minor abilities provide all-around vision (no flanking; mainly useful in strategy-focused games), an orb that can effectively cast undeath to death on undead you smack around, the ability to place a mark of justice on creatures, and access to temporal vision. This access to knowledge and information requires smart applications, but that banishing power is, all by itself, very strong when used well. Don't underestimate this spirit.
Essex Avix - Action Economy
Essex Avix is easily one of the most powerful spirits you can bind. Its major ability, Split the Twins, allows you to create a double of yourself and get a second turn every five rounds. You take twice the damage for one round after using it, which is risky, but action economy is the most valuable thing in the game and the ability to get an entire extra turn essentially at-will is straight-up amazing for many builds. Doubly so if you can protect yourself from harm.
Speaking of protecting yourself, the Unwilling Shield ability allows you to forcibly split the damage you'd take with an enemy, largely removing the penalty of the major ability. The Titanic Growth power also lets you grow in size, which can further augment the power of a second turn. Whether you're a martial warrior or a caster, this is a very powerful choice. The other abilities are largely flavor powers and have much less of an impact.
Evening Star - Generalist
Evening Star is essentially a generalist spirit, with a major ability that allows you to inflict solid damage on targets within 20 feet. Note: It hits targets, not all creatures, which means you can avoid hitting your allies. It also allows you to use gaseous form - a useful utility option - and transform into a troll. Healing is nice, isn't it? The other abilities are largely ribbons, but this is a fairly solid option for anyone. The ability to frighten animals (as Turn Undead, but animals) will rarely see use, and the ability to use Ventriloquism has some power for creative players.
Goliath - Combat (Pain)
Goliath is a solid combat/pain spirit, with a major ability that acts as the chain of perdition spell, although its use of Charisma means this isn't very viable on any non-Charisma build. Goliath also has a symbol of pain effect, access to Great Fortitude and Improved Great Fortitude, and the ability to use the chains you create as a powerfully-enchanted weapon. This instant access to an enchanted weapon could save a lot of money, and certainly be worth some ways to access it. The ability to gain DR 10/- is also a significant defensive boon against many foes. Overall, there's a lot to love here if you enjoy getting up close and person.
Hou-ou - Fire/Life
Hou-ou is a phoenix-themed Starless spirit (so it's easier for most people to access it), and one of the relatively rare good spirits at this level. Its major ability is creating a wall of fire, which is mainly useful for battlefield control, but the capstone lets you do it as a swift or immediate action. Casting any spell as a swift action makes it instantly more valuable.
The rest of this phoenix's powers are mainly about healing, with the ability to gain regeneration, cast mass cure serious wounds a decent number of times, and return to life as through resurrection. You can only do this once every 24 hours, but it's still a very powerful recovery spirit when you consider all the options. You can also get bonuses to Intelligence-based checks, which can make it easier to bind other spirits if you can get several at once. All-in-all, a pretty good choice for high-level characters.
Mana - Beholder
Mana basically turns you into a beholder. Its basic power allows you to deal 1d6/2 levels in rare damage types as a close-range ray, but you can fire four rays if you're showing this spirit's sign. Its capstone lets you bypass most defenses, and as a touch attack at this level, it's practically guaranteed to hit. With potentially 4x your level in d6's, that's pretty good!
Its other abilities include all-around vision, the ability to view magical auras at-will, the ability to create an antimagic cone, the ability to undo most types of magic, and a gaze attack that can stun your enemies. There's a lot of powerful magic/antimagic here, and Mana can ruin the day for a lot of powerful casters. Basically, this is a good choice for everyone.
Mother Medusa - Petrification/Poison
This spirit does pretty much exactly what you'd expect. Its major ability lets you turn your hair into snakes that can attack foes and inflict a Dex-damaging poison. The capstone is a must at this level, because it lets you bypass immunity to poison (fairly common) and negates resistance bonuses against the ability.
It also has a solid combo with its other abilities, including an aura that forces creatures to look at you if they're close (this hits allies), and the ability to then use a gaze attack to turn them to stone. The frightful presence just makes being around you even worse. The spell resistance against curses is very situational, but could be handy. Overall, a solid battlefield control spirit, if a bit limited on range. This works best on characters with a lot of hit points.
Overmind - Defense
Overmind is kind of the opposite of Doomed Salu'im. It allows you to eject yourself from time for awhile, and as an immediate action, which allows you to straight-up dodge almost anything that could hit you. With the capstone, you can perceive what's going on and choose to return early, giving you outstanding utility. It doesn't recharge while you're gone, but it's still a rather consistent defense throughout the day.
This spirit also gives large bonuses on Perception and Sense Motive (both very useful skills), as well as a bonus against traps and the ability to block extradimensional movement from enemies. The improvement to initiative and the ability to use arcane eye are less immediately impactful, but still generally useful. Overall, a solid spirit, if weighted pretty strong towards defense.
Rajah Amajaloma - Combat
Rajah Amajaloma is a powerful combat spirit, with a negative energy ray that does 2d6 damage per level. Fort saves reduce this, but it still deals impressive damage for a binder power. This spirit further gives great defense against poison, fire, and electricity, plus spell resistance against divine spells, and a constant nondetection and trackless step effect that can make you very hard to find. The blight power that wrecks plants is rarely useful, but it does have some things to stop foes from fleeing.
The negative energy ray isn't a substitute for a normal attack on a character, but the utility effects are all top-notch, making this particularly good as a secondary spirit for anyone who needs some extra defenses and damage.
Roshar - Restoration
Roshar is basically the biblical Moses. His primary power lets you attack all creatures and objects within 20 feet for relatively low fire damage. This isn't particularly impressive except against a group of foes with low HP, which means bosses are out, but the capstone turns half of the damage to untyped and can thus hit basically anything.
The minor abilities include emitting an aura of light at will, using a greater restoration effect, transforming wood into snakes (and commanding reptiles), and a nice bonus on some travel/survival skill stuff. I don't think the major ability is useful enough at this level for most people to want it, but the access to many uses of a powerful restoration spell can be useful against certain types of foes. Treat this as a secondary spirit for most people.
Ryoku Ria - Hostile Polymorphing
Ryoku Ria is an animal-focused spirit, with a major ability that allows you to polymorph a foe to remove an attack or, with the capstone, remove some special abilities. This can straight-up cripple some monsters, although its value varies heavily based on the types of foes you fight and how much you know about them.
The minor abilities allow you to grant animal aspects to allies (on an ongoing basis), cast the animal shapes spell, cast the polymorph any object spell repeatedly, and take on a form you want (as greater polymorph). People who've played the Shifter from Spheres of Power will grasp this pretty well, but the simple fact is that Ryoku Ria has incredible utility potential when played by a well-informed user. Definitely a contender as a secondary spirit, and with enough utility to even qualify as a primary spirit.
Septigenius Maximus - Debuffing
Septigenius Maximus is relatively similar to Mother Medusa in its focus on debuffing enemies. The major ability lets you transform a target into a chosen material (or, with the capstone, restore petrified creatures), while the minor powers can essentially turn you into a mummy and stun foes with ecstasy. Immunity to poison and acid are useful secondary powers, as is the ability to remove disease and poison from allies. Not a top choice, but a solid generalist/debuffer, and certainly not a bad option for many builds.
Solterra - Healing/Battlefield Control
Solterra is a healing/removal spirit, with a major ability that lets you banish or imprison most types of enemies. Minor abilities include dispelling illusions and polymorphs, terraforming the land, casting regenerate on creatures once per day per creature, and disintegrating certain types of foes regularly. These are some very powerful effects, if limited by creature type, making Solterra somewhat campaign-dependent but generally very worthwhile.
Young Krios - Heads
Young Krios is a head-focused spirit, with a major ability that shrinks the foe's head. This debuffs their mental scores, which can significantly reduce their abilities and leave them vulnerable to followups. Minor abilities include cursing foes with a variety of options, gaining a vorpal effect on a melee touch attack, bonuses to some skills, and a nondetection with bonus immunity to thought-reading. This is a pretty solid combo, although the vorpal attack is less-useful for anyone who already has a good attack routine.
Level 9 Spirits
Finally, we're at the capstone - the most powerful and hard-to-get spirits. Some have very high Binding DCs, so make sure your skills are up to par!
Alabaster - Time/Space
Alabaster is a time/space spirit and a good choice in general for binders. It allows you to use a time stop effect, with added immunity to environmental problems with the capstone, and its minor effects include enhanced Intelligence (does not stack with headbands, so of dubious value), the ability to create a wormhole reaching up to 100 feet (unlimited uses), the ability to cast mirage arcana, and immunity to negative levels and death effects.
The vestigal boon lets you trade out the major ability for an automatic true resurrection, which is followed by being in a poor pact for a month. I think the regular major ability is better, but this is a great backup option for a truly deadly fight.
Aladdar - Freedom and Movement
Aladdar is a freedom-focused spirit that allows you to use a disjunction effect with a touch, as well as the knock spell at-will. He also grants immunity to effects like imprisonment, many uses of the freedom of movement spell, access to greater invisibility, and a large bonus to your initiative. These are generally good utility effects in general, but are particularly potent when you use them to enable other options. Ultimately, Aladdar is a solid choice for most characters.
Ashvattha - Teleportation/Miracles
Ashvattha is one of the most powerful spirits period. Its major ability allows you to teleport foes away (with a particularly nasty capstone that can eject people onto other planets entirely), and minor abilities that let you animate trees, speak with plants, and gain tremorsense. Those are mostly just ribbon powers, though, because Ashvattha also lets you cast miracle as a spell-like ability, realistically 10+ times per day. It doesn't let you use effects that require expensive material components, but that's still one of the most powerful utility options in the game, bar none. Literally everyone can get great use out of this spirit, so it's a top choice for this level.
The Beast That Births - Motherhood
No, it's not Lamashtu. Probably. TBTB allows you to summon monsters to fight for you (as summon monster IX, except just one monster unless you get the capstone), which is a great and incredibly flexible power all by itself. It also allows you to consume the blood of recently-slain enemies to heal (useful if you're lacking other options), transform into a large creature with bonuses (plan for these), cast wail of the banshee, and gain a constant spirit birth spell. This allows you to have accelerated pregnancies, which is... not useful for most campaigns, actually, but interesting. Overall, not the best 9th-level spirit.
Brother Calvis - Defense
Brother Calvis is a defensive spirit, and therefore useful for pretty much everyone. His capstone allows you to simply straight-up nullify a harmful effect, and with the capstone, you don't need an action for it. This is one of the most powerful protective abilities in the game. He also lets you banish a foe from reality for a bit (that shows up a lot), protects you from being flat-footed or denied your Dexterity bonus to AC (good against rogue-types), lets you cast haste on yourself at-will, and straight-up immunity to mind-affecting powers.
This spirit is simply great for everyone, but especially for warrior types who have lower Will saves. Defensive packages don't get much better than this, and he's probably worth a permanent pact if you can get one.
Daeminthos - Generalist
Daeminthos is a psychic (or, in some games, psionic) spirit with a general build. The major ability essentially does 2d6 damage per level (with half of that to all targets within 10 feet of your foe), and minor abilities that include hold monster, blindsense for 60 feet, and telepathy with decent range. However, the Psychic Foresight is the really meaty bit here, offering a +10 insight bonus to any d20 roll as a swift action (i.e. on your turn). That can help ensure your low rolls hit, making you consistently better at using riskier options. It's not as strong as Ashvattha or Brother Calvis, but it's a decent spirit all the same.
Dama - Buffing
Dama is a buffing spirit, with a major ability that lets you gain any feat you meet the prerequisites for (except those with limited uses). That's an answer to a whole lot of problems. The minor powers let you compress and alter your shape, gain a +6 enhancement bonus to Constitution (useful if you can't afford the belt), a +4 insight bonus on all skills you're trained in, and the ability to just straight-up kill humanoids and reincarnate them as humans. That can remove a lot of racial powers, and it's pretty fearsome. Dama isn't a top spirit, but don't underestimate it.
Eschalon - Undeath
Eschalon is an undeath-focused spirit with a major ability that's a slightly better version of Roshar's, including built-in untypes damage and the ability to nauseate foes for a bit. The Capstone is tricky because it removes the Reflex save, but foes have to take that in order to have the risk of being nauseated.
Eschalon also lets you soul bind creatures to deny them the afterlife, gives you a permanent desecration effect that buffs nearby undead, lets you use a Power Word Kill effect and command lots of undead, and cast cursed earth once per day. Essentially, you're an instant (and pretty decent) necromancer.
Kaylos - Genie/Wishes
If Eschalon turns you into a necromancer, Kaylos turns you into a genie. You can open a rift to the Elemental Plane of Fire; it's not great damage because so many foes resist fire, but the capstone of teleporting it to the plane of fire is a great banishment option. Kaylos also offers boosts to several binder-relevant skills and gives you access to the Destruction domain's spell-like abilities. If you can bind Kaylos at all, you get the whole list.
The real power here, though, is the Twisted Wish power. You have to provide material components as needed, but if you can get foes to confess their Sinful Desires to you with another power, you can just straight-up grant their wishes while also harming them. Overall, this offers incredible flexibility, making it a top choice in general.
King Mutaros - Destruction
King Mutaros is a destructive spirit. His major ability grants you 1d6 lightning/sonic damage, but only to a foe within 10 feet, which limits its value. The capstone maximizes this, though, which is pretty great damage in general. He also lets you repeatedly cast earthquake, create a lower-damage sonic attack, and just straight-up kill any creature in 30 feet (except you) that fails a Fortitude save. This is a poison effect, but still. Nasty. Oh, and you get regeneration 5 (suppressed by piercing and bleed, the former of which is common-ish), which is also great throughout the day. The King is death in a can, basically, and can augment most caster types quite nicely. Warriors will do better with a different spirit, though.
Malebolge Moors - Generalist
Malebolge Moors is a generalist spirit similar to Rajah Amajaloma, with a major ability that acts as power word stun (the capstone increases the hit point range you can effect) and minor abilities that include a melee touch attack for dealing fire/untyped/charisma damage, resistance to acid and cold, immunity to fire, poison, and pain effects, and the ability to cast greater dispel magic as an immediate action on targets within 30 feet. This doesn't refresh daily, so Malebolge Moors is a poor choice for a permanent spirit, but otherwise has a solid blend of options.
Prometheus - Fire
Prometheus is a fire-themed spirit, which is of limited value because, again, so many foes resist it. The major ability lets you use a fire breath attack (with a capstone to give that half untyped damage so many spirits at these levels offer), plus the ability to turn into a red or gold dragon, create an overwhelming presence, create a fire shield, and hold onto a draconic reservoir for absorbing fire damage. There's some additional production of flames and healing, but overall, the dragon transformation is the main draw here. Prometheus is a bit lacking overall, and I'd treat him as a secondary spirit.
Saint Alexandra - Pact Spirits
Saint Alexandra is only good for true pactmakers because most of its powers affect your other spirits, and you need multiple spirits to get the value from this. Her capstone lets you give your major abilities to other people, which can be helpful if the need something else to do. Or, you know, give it to a familiar or NPC with open actions. She also lets bonuses from minor abilities stack, cast Pact Magic domain spells, expend some abilities to recharge others faster, and gain a reliable pact at the cost of not getting a capstone.
Whether the ability to shuffle and stack things is useful depends on the spirits you get, so it's hard to pinpoint her full value, especially compared to the value of getting another spirit you can use more actively. Thus, Saint Alexandara is variable for pactmakers, but terrible for everyone else.
Tartarus - Banishment
Tartarus has the highest binding DC of all spirits, at 50. The main power is essentially a black tentacles spell that grapples foes and tries to banish them with a plane shift power, while the minor abilities let you create hungry pits, make wails of the banshee, and create a wall of suppression. The Lore of the Dead lets you automatically know the abilities and weaknesses of any creature you encounter, which can be quite useful if people have trouble with knowledge checks. This is a hard spirit to get, but if you can lower a foe's resistance to the tentacles, you can banish almost anyone. It's no 10+ uses of Miracle, but that does tend to end fights.
I recommend taking the vestigal boon, which swaps the banshee wail for the ability to turn slain enemies into ghosts that fight on your behalf for about two minutes.
The Worglord - Grappling/Heroics
The Worglord is quite amazing. The major ability lets you Take 20 on a roll as a swift action, or maximize almost any effect if you have the capstone. That is absolutely incredible on some builds. He also allows you to suffocate foes while grappling them, gain a large insight bonus on a saving throw roll, gain the same sort of bonus to Strength or Dexterity-based checks, and gain a +6 enhancement bonus to Strength and Constitution. This spirit stacks particularly well with grapple-focused spirits or builds. If you also have The Beast That Births bound, you can use the vestigal bond to get a pounce effect after you charge foes.
This spirit is great to start with on any melee build, but especially powerful with spirits like Gulguthriana or Noble Marius.