Summoner Handbook: PF2 Class Guide

Introduction

The Summoner is the ultimate pet class in Pathfinder 2e, granting you a powerful, customizable creature called an “Eidolon”. The Eidolon allows you to change your role within the party, allowing your dynamic duo to serve as a Defender, Scout, and Striker, while the Summoner can serve as a Face with some light Blaster, Healer, and Support options from their Bounded Spellcasting.

While building an effective Summoner can be complicated, it’s not so complicated as building two wholly independent characters. Keep in mind the role you want your Eidolon to play, and look for options which clearly play to that role. Plan your spellcasting around your Eidolon’s capabilities, and be sure to bring some cantrips to fill various needs.

The complexity in the Summoner comes from managing their action economy. A typical character gets three Actions, potentially stretching that with things like Minions. But the Summoner’s Act Together action lets you overlap actions with your Eidolon, allowing you to take up to 4 Actions in a single turn without involving Minions or the Quickened condition (5 with Tandem Movement!). But you also need to consider positioning both yourself and your Eidolon in order to keep both of you safe, but still a position to be useful.

If you look at the Summoner and think “I want a cool monster but I don’t want to juggle all the complicated action stuff”, look at the Meld With Eidolon feat. It changes the function of the Summoner from a player-pet setup into a transformation sequence thing, allowing you to split your focus depending on whether you’re in or out of combat.

You may also find these supporting articles helpful:

Disclaimer

RPGBOT uses the color coding scheme which has become common among Pathfinder build handbooks.

Red: Bad, useless options, or options which are extremely situational. Nearly never useful.
Orange: OK options, or useful options that only apply in rare circumstances. Useful sometimes.
Green: Good options. Useful often.
Blue: Fantastic options, often essential to the function of your character. Useful very frequently.

Summoner Class Features

Key Ability: Charisma. Keep in mind that since the Summoner doesn’t rely solely on spells to attack, you don’t need to maximize Charisma as much as you would for most spellcasters.

Hit Points: Most eidolons fight in melee, so sharing 10+ hit points between yourself and your eidolon makes that much for manageable.

Proficiencies: These proficiencies are weak. You’re bad attacking with both weapons and spells. Your AC is attrocious and your saves aren’t impressive. You don’t get a noteworthy number of skills, and your Perception is going to be poor. Hopefully your Eidolon can do a lot of the hard work.

Perception: Middling Perception and no dependence on Wisdom, so expect to be bat at Perception.
Saving Throws: Above average Fortitude, horrible Reflex, and average Will saves. You’re unarmored, so Dexterity can make up the gap with Reflex saves, and the Summoner is very SAD so you can afford to invest a bit in Constitution and Wisdom to support your other saves.
Skills: 3+Int and your Eidolon will usually give you two. That’s slightly above the average of 4+Int, but Intelligence is also a dump stat for the Summoner.
Attacks: Only simple weapons and your progression is as bad as it gets. You’re right down there with the Wizard.
Defenses: No armor and you’re tied for the worst Unarmored Defense progression in the game with classes like the Wizard.
Spellcasting DC: Your spellcasting proficiency is as good as classes like the Champion, the Magus, and the Monk, none of which rely on spellcasting offensively. This is especially frustrating because your eidolon uses your spellcasting attack bonus and save DC.

Eidolon: See my Summoner Eidolons Breakdown.

Manifest Eidolon: Central to how the Summoner functions. This takes three Actions and your Eidolon’s presence doesn’t have an expiration, so you should almost always have your Eidolon manifested. Avoid manifesting it in combat as much as possible because doing so eats a full turn.

Act Together: Effectively gives you 4 Actions per turn to share between yourself and your Eidolon.

Share Senses: For many summoners, your Eidolon will be better at going places and doing things due a combination of better movement options, better defenses, and sharing your skill proficiencies. Share Senses allows you to capitalize on this by sensing through your Eidolon while it’s off exploring in your stead, and if your Eidolon is in danger you can un-manifest it and Manifest it again a moment later. However, this doesn’t let you communicate instructions to your Eidolon, so be sure to have a nice conversation with them before you send them off to leap into traps or whatever.

Summoner Spellcasting: The Summoner is a “Bounded Spellcaster” like the Magus, so they get at most four spell slots by default, but they’re all high level. This means that casting leveled spells is a complement to your other capabilities rather than your central, defining feature.

Heightened Spells: Heightening spells is an important mechanic in Pathfinder 2e. Many important spells scale with spell level, allowing them to stay relevant long after you first learned them. Since the Summoner is a Bounded Spellcaster, you’ll spend a lot of time heightening lower-level spells. Fortunately, when you hit level 3 and get 2nd-level spells you’ll also get Unlimited Signature Spells.
Cantrips: Fantastic every time, on any character, in any amount. Summoners learn 5 cantrips at level 1 and never get more, but you can replace them by retraining or when you gain a level so you’re not locked into whatever you pick at first level.
Spell Repertoire: You get at most 5 spells known (though you can add to that with other options like Ancestry Feats), so you need to be very picky about what spells you learn.

Link Spells: See Summoner Focus Spells, below.

Unlimited Signature Spells: The Summoner knows at most 5 spells, so it’s helpful that they’re all Signature Spells.

Instant Manifestation: Useful if you’re somehow dragged into combat without your Eidolon handy, but that should not happen frequently.

Summoner Ability Scores

The typical Summoner’s ability scores closely resemble the Sorcerer. However, since the Summoner isn’t a full spellcaster, their Charisma isn’t applied as frequently as it is for Sorcerers and other spellcasters. This gives you room to reduce your investment in Charisma and put those resources elsewhere, especially if you want to fill in gaps in the Summoner’s defenses.

However, not every summoner necessarily needs to be built this way. If you take the Meld With Eidolon feat, your own ability scores are less impactful defensively. You can likely afford to dump Dexterity and Wisdom since you’ll be relying on your Eidolon’s defenses instead, leaving you room to invest those ability scores however you like, such as investing more in Intelligence to support your skills. Regardless, you do need Constitution to support your shared pool of hit points, and you need enough Charisma to support whatever you intend to do with your spells. Though, even that may be a minor need if you don’t intend to your spells offensively.

Str: You do not belong in melee, and even if you’re in melee you can use Gouging Claw rather than a weapon. Dump this.

Dex: AC and Dexterity saves. Crucial for staying alive.

Con: You have terrible armor and you share hit points with your Eidolon. Your Constitution score should be as good as you can get it.

Int: Generally all that you get is skills, but if you take an Eidolon with the Arcane or Occult tradition and want to use Extend Boost, you’ll need enough Intelligence to support the appropriate skill check.

Wis: Perception nad Will saves.

Cha: Your Key Ability score. If you plan to rely on offensive spellcasting in combat (cantrips, spells cast by your Eidolon, etc.), you want to maximize this. If you’re going to rely more heavily on your Eidolon’s Strikes, there’s much less pressure so you can afford to distribute your boosts elsewhere. It’s technically possible to play a Summoner with low Charisma if your spellcasting is all buffs and utility options, but that will strictly limit your spellcasting options, so I don’t recommend it.

Summoner Ancestries

Constitution boosts are absolutely essential, as are any other improvements to your durability like high Ancestry hit points or damage resistances. Charisma boosts are great, but how much you need them depends on how you plan to use your spells. If you’re planning to blast stuff with cantrips, you need Charisma. If you want buffs and utility spells, you can go easy on Charisma.

Because summoners have such limited spellcasting, innate spells are a great addition. Additional skills can also be helpful to compensate for your dumped Intelligence, especially since your Eidolon shares your skill proficiencies.

Weapon proficiencies are outright useless for the Summoner, as are improvements to unarmed strikes.

Catfolk^APG: A Wisdom flaw isn’t ideal, but it won’t ruin you. The Catfolk’s feat options aren’t fantastic for the Summoner, but the Cat’s Luck feat chain is good.

Dwarf^CRB: Use the optional flaw rule to put a -2 in Strength and Intelligence, then put both Free Boosts into Charisma, so you end up with +2 to Dex/Con/Cha. Eventually pick up Mountain’s Stoutness, giving you bunch of extra hit points. Defensively, the dwarf is very durable, but it won’t help you actively accomplish anything except survive. Consider Adopted Ancestry.

Elf^CRB: The elf really wants high Dexterity and Intelligence, but their Constitution Flaw and low ancestry hit points are hard to offset. Elven Lore can get you some extra knowledge skills and Otherworldly Magic can get you a cantrip, but juggling the flaws and boosts really isn’t worth the effort.

Gnome^CRB: Borderline perfect for the Summoner. Boosts you want, flaw in an Ability Score that you don’t care about, and several good feat options. The starting hp is low, but not problematic. Empathetic Please is a great way to mitigate attacks against yourself, and you can get cantrips from both the Wellspring Gnome Heritage and from First World Magic. As you gain levels, feats like Energized Font and First-World Adept are easy additions.

Goblin^CRB: A wisdom flaw isn’t ideal, but it’s survivable and you can still get boosts to both Constitution and Charisma. Goblin Scuttle works very well with your Eidolon, allowing you to stretch your action economy even further to get a Step as a Reaction. Goblin Lore is decent, and Goblin Song can be a good debuff for your enemies if you have offensive spellcasters in the party.

Halfling^CRB: Good Ability Scores, but not few easy feat options. Halfling Luck always works, and Intuitive Cooperation is great if you plan to use Aid with your Eidolon (and you probably should).

Human^CRB: Fantastic and versatile. Cooperative Nature is great for aiding your allies, including your Eidolon. Courteous Comeback is great for being a Face. Adapted Cantrip can get Gouging Claw onto the Divine and Occult spell lists. You have a lot of really great options here. If you go for the Half-Orc Ancestry, Orc Ferocity can keep you conscious when you and/or your Eidolon fall to 0 hp.

Kobold^APG: A Constitution flaw hurts, so use the optional flaw rules to drump Strength and Intelligence for a second Free Boost, and put both Free Boosts into Constitution so you’re getting +2 to each of Dex/Con/Cha. You have several excellent feat options. Grab Cringe to mitigate damage from the occasional attacks that come your way. Kobold Breath offers a good AOE damage option which will complement your spellcasting. At higher levels, the Dracomancer and Winglets feats are fantastic.

Orc^APG: The ability boosts are difficult and you have almost no feat options which appeal to the Summoner.

Ratfolk^APG: The ability boosts/flaws are fine, but the Rafolk offers almost no feat options which appeal to the Summoner.

Tengu^APG: The ability boosts work fine, but use the Optional Flaw rules to get an extra Free Boost so you can get +2 Dex/Con/Cha. There aren’t many feat options here, but Squawk is good for a Face, and the Skyborn Heritage offers some feats which will let you fly at higher levels.

Summoner Backgrounds

Ideally you want boosts to Constitution and Charisma, but beyond that you have a lot of room to explore.

If you’re having trouble deciding, here are some suggestions:

Academy Dropout
Eidolon Contact – I know, this one’s pretty obvious

Summoner Skills and Skill Feats

You get Skill Increases at 3rd and 5th level to raise skills to Expert, increases at 7th, 9th, 11th, and 13th level to raise skills to Master, and increases at 15th, 17th, and 19th level to raise skills to Legendary. That means that you can maximize at most three skills, and the rest of your skills might not advance beyond Trained.

You get Skill Feats at even-numbered levels, giving you a total of 10 Skill Feats (and maybe another from your Background) by 20th level. Generally, you want to invest these feats in the same skills which you are choosing to maximize, though in some cases you may want to grab feats from skills which don’t require that you be more than Trained.

Skills for the Summoner are a little bit odd because your Eidolon uses your Proficiency but their own ability scores, meaning that the skills which work for you and the skills that work for your Eidolon may differ. It’s entirely possible that between you and your Eidolon you could be effective at any skill. However, Intelligence is a dump state for the Summoner and none of the pubished Eidolon options have great Intelligence, so Int-based skills are a difficult choice.

Despite using your proficiency in skills, your Eidolon does not get to use your Skill Feats. If you take feats which give you new skill options, your Eidolon does not benefit. For example: If you take Battle Medicine, your Eidolon can’t use the new Action granted by the feat. If you take Titan Wrestler, your Eidolon does not gain the ability to grapple larger creatures than it usually could.

Acrobatics (Dex): Helpful if you plan to take a feat that gives your Eidolon a fly speed.
Arcana (Int): Helpful, but Int-based skills are hard for the Summoner.
Athletics (Str): Many Eidolons can start with 18 Strength, and if you’re treating your Eidolon like a pet fighter, proficiency in Athletics makes Disarm/Trip/Shove effective tactical options.
Crafting (Int): Helpful, but Int-based skills are hard for the Summoner.
Deception (Cha): An essential Face skill.
- Lie to Me^CRB: The Summoner’s Perception progression is bad, so Lie to Me will make you much harder to lie to.
Diplomacy (Cha): The king of Face skills.
Intimidation (Cha): An important Face skill, and Demoralize is very appealing in combat.
- Battlecry: Demoralize for free when combat starts.It’s a free debuff at the beginning of every fight.
- Intimidating Glare^CRB: A frustratingly large number of enemies won’t understand Common, so removing the Auditory trait makes Demoralize much easier to use.
- Terrified Retreat: Counting on a critical success is hard, but if your Charisma is very high it might work.
- Scare to Death: Spend one Action to pick out the creature in the room the lowest Will save and kill them or send them fleeing. Repeat until the room is cleared. At this point you only need to fight things that are strong enough to threaten your whole party on their own, and even then this can still replace the Demoralize action almost entirely.
Lore (Int): Lore skills are too vague and too numerous, and you likely don’t have enough skills to throw about to justify going beyond Trained.
Medicine (Wis): Every party needs someone to be good at Medicine. It doesn’t need to be you, but since you’re two characters you can heal twice as many people at once. Unfortunately, your Eidolon won’t benefit from stable Skill Feats like Continual Recovery and Ward Medic. But it does mean that you and your Eidolon can heal each other, applying the results to the same pool of hit points. It’s more of a mechanical novelty than an exploit, but the idea of bandaging someone else until you feel better is fun to think about.
Nature (Wis): A helpful knowledge skill and you’ll likely have passable Wisdom.
Occultism (Int): Helpful, but Int-based skills are hard for the Summoner.
Performance (Cha): Too situational.
Religion (Wis): A helpful knowledge skill and you’ll likely have passable Wisdom.
Society (Int): Helpful, but Int-based skills are hard for the Summoner.
Stealth (Dex): You’re no rogue, but you or your Eidolon might have enough to back this up.
Survival (Wis): Too situational.
Thievery (Dex): You’re no rogue, but you or your Eidolon might have enough to back this up.

General Skill Feats

Dubious Knowledge: You’ll end up with at least one knowledge skill and it might be Intelligence-based. Dubious Knowledge makes those checks a little more useful. Not great, but it’s something.

Summoner Feats

Class Feats

1st Level

Advanced Weaponry^SoM: Not always necessary, but if you’re building around your Eidolon using things like Shove and Trip, this allows you to select more than one of those options.
Dual Studies^SoM: If you’re short on skills but still want to cover more of them, this is a great way to get yourself a skill that your Eidolon won’t use like Persuasion and to get your Eidolon a skill you won’t use like Athletics.
Energy Heart^SoM: The damage resistance scales very slowly, but dealing energy damage gives your Eidolon a way to get around physical damage resistances. Note that this only changes the damage type of one of your Eidolon’s unarmed strikes. Eidolons start with two and you can add more with things like Ranged Combatant, so even if you pick something like fire for your damage type, you still have other attack options if resistance/immunity become an issue.
I’m not certain what is intended to happen if you add Versatile (B, P, S) to the unarmed strike you choose with Energy Heart. It seems RAW that if you take Advanced Weaponry and choose Versatile, your Eidolon’s unarmed strike could pile on multiple damage type options.

Also keep in mind how multiple damage resistances work in PF2: if multiple resistances would apply, you use only the highest. Energy Heart’s damage resistance is nice because it’s persistent, but Reinforce Eidolon covers all damage, making it consistently useful in every encounter. Fire damage is common, but it’s not universal, so you may go through many encounters where Energy Heart’s damage resistance isn’t useful, and if you pick less common damage types you might go long stretches without seeing acid or lightning damage.
Expanded Senses^SoM: Scent is a great way to find hidden and invisible creatures.
Extend Boost^SoM: See Extend Boost under Focus Spells, below.
Glider Form^SoM: Very situational by design, and the fact that it can’t be activated as a Reaction means that your Eidolon is still vulnerable to falling unless you spend the Action to glide. Your best use case is to climb something, then jump and glide around for a bit. But even then, that’s a lot of actions and at least two feats to mildly inconvenience your enemies while they’re busy killing your friends. Unfortunately, this is a prerequisite for flight later. I recommend taking a different feat at early levels, then retrain it into this.
Meld Into Eidolon^SoM: In 1st edition, the Synthesist was a massively powerful version of the Summoner, turning you into a crazy fighting machine with a mountain of stats. This feat fills that conceptual niche. However, it has none of the things that made the synthesist powerful, and while it shares the concept, it is very much its own beast mechanically speaking.
The benefits and drawbacks of this feat are complex to say the least. You are no longer targetable from two places, so you no longer need to worry about your own poor defenses. You’re free to build your ability scores almost however you like, such is by dumping Dexterity and boosting Intelligence for additional skills. So defensively, this holds some appeal. As you add additional capabilities to your Eidolon like movement speeds, it can also make traveling much easier. Turn your eidolon into a tiny flying creature and you can go basically anywhere easily and with little hassle.

However, you give up the benefits of Act Together. The ability to overlap your actions means that you can get more actions in a single turn than most creatures, means that you can accomplish a lot within a single turn. You can set up combos, buff your Eidolon, heal yourself (and therefore your Eidolon), Aid your allies, or any manner of other things. Without separating from your Eidolon, you give up those potentially powerful options for safety.

Using Meld Into Eidolon is a complicated trade. You need to build your whole character around it if you want it to be a mechanically impactful option. The ability to focus solely on the needs of your Eidolon does make the Summoner much simpler to play, but not necessarily better.
Unfettered Eidolon^SoM: See Unfettered Eidolon under Focus Spells, below.

2nd Level

Alacritous Action^SoM: Movement in PF2 is costly and impactful, and a 10-foot bonus to speed can make a big difference.
Amphibious Form^SoM: Only situationally useful. If you’re in a semi-aquatic campaign (think pirate ships), this may be worthwhile. Otherwise, Evolution Surge will do the job.
Magical Understudy^SoM: Relying on cantrips means automatic damage scaling without the need to invest in expensive handwraps, so if you wanted to put gold other places, cantrips may be the solution. This is also a prerequisite for the other feats which grant your Eidolon leveled spells.
Ranged Combatant^SoM: Useful, but the damage die is small. If your Eidolon can get out of reach by climbing or flying, this allows it to fight from a safe distance. But this won’t compete with your fellow players using weapon options like bows.
Reinforce Eidolon^SoM: See Reinforce Eidolon under Focus Spells, below.
Steed Form^SoM: Riding your Eidolon makes it easier to get out of dangerous places without cutting into your action economy by spending two Actions to move each body. However, it also makes you much more vulnerable to area damage. Use with caution and don’t be afraid to dismount if you meet a hostile spellcaster or something with a breath weapon.

4th Level

Bloodletting Claws^SoM: Persistent damage is really good. The scaling isn’t amazing, but it’s something. If you’re consistently having your Eidolon make numerous Strikes in a turn, this should pay off frequently.
Defend Summoner^SoM: Or you could use the same action to Raise a Shield to get exactly the same bonus. It’s not like you’re doing anything exciting with your hands except casting spells, and you can do that one-handed.
Dual Energy Heart^SoM: Energy Heart might mean that you “dump” one of your Eidolon’s attack options so that you can get resistance to a common damage type like fire. This makes that attack more useful and provides another persistent damage resistance. If you pair cold and fire (two common types of energy damage) your Eidolon will enjoy resistance to common damage types while also being able to work around most resistances/immunities to its own attacks. However, be cautious about over-investing in damage resistances like this. Reinforce Eidolon may be both less costly and more effective.
Lifelink Surge^SoM: See Lifelink Surge under Focus Spells, below.
Reactive Dismissal^SoM: Only situationally useful. If you’re using this consistently in combat, you need to reconsider your tactics. This might reduce damage enough that you don’t fall unconscious, but you don’t want that to be a go-to tactic because it means you’re taking more damage than you can handle.
This may be unusually useful when paired with Unfetter Eidolon, allowing you to send your Eidolon off to somewhere dangerous on its own, then use Reactive Dismissal if it would be seriously injured.
Shrink Down^SoM: Only situationally useful. This becomes more important if you add feats which increase your Eidolon’s size because it’s difficult to walk a Huge creature through a doorway designed for humans.
Skilled Partner^SoM: Three skill feats can do a lot. Common options like Battle Cry are easy choices, but you might also go for feats to support the Medicine skill or skill feats which make your Eidolon a more effective Scout.
Tandem Movement^SoM: Unless you’re riding your Eidolon, you’ll frequently find yourselves in situations where both need to move but only have one Action between you if you still want to do cool stuff on your turn. This neatly solves that challenge, making it that much easier to squeeze some more out of your action economy..
Vibration Sense^SoM: I think Expanded Senses is a better choice unless you’re in an aquatic campaign where Scent won’t be effective.

6th Level

Blood Frenzy^SoM: Triggering this is unreliable, and dropping your Eidolon’s AC by 2 is risky despite the small pool of temporary hit points. I don’t think you can offset it with Reinforce Eidolon, either. If your Eidolon has permanent damage resistances from other sources, this might be worthwhile, but otherwise it’s a risky gamble that you won’t get to use consistently even in the best of cases.
Eidolon’s Opportunity^SoM: A huge tactical advantage in almost any encounter, provided that your Eidolon is built for melee strikes (ranged attackers and cantrip-users may still benefit, but less so). This gets even better if you make your Eidolon larger.
Eidolon’s Wrath^SoM: See Eidolon’s Wrath under Focus Spells, below.
Master Summoner^SoM: More spell slots is a big improvement for the Summoner, and summon spells can be extremely powerful and versatile. Just make sure that you know several summon spells and have a good grasp on what your summon options are. You can also use this for Incarnate spells, which are like high-level blast spells disguised as one-round summons.
Ostentatious Arrival^SoM: Very little damage and you shouldn’t be manifesting your Eidolon in combat unless something weird has happened. Once you get Instant Manifestation at 19th level this becomes more viable, but it’s still not amazing.
Phase Out^SoM: For eidolons built around spellcasting, this has no drawback. This is also helpful if your Eidolon is scouting or if you just need it to tank for a few turns.
Tandem Strike^SoM: Your weapon proficiencies are absolutely atrocious, any gold you put into weapons need to go into handwraps to power your Eidolon, and you have absolutely no class options to make your own unarmed strikes meaningful. This is outright worse in almost every sense than just having your Eidolon make two strikes.

8th Level

Boost Summons^SoM: Very useful if you’re relying heavily on summoned creatures, but be mindful of your action economy. One Action to Sustain the Spell, one to cast Boost Eidolon, and you have one left for your Eidolon (two if you overlap with Act Together). The damage bonus from Boost Eidolon scales based on your Eidolon’s number of damage dice, so if you’re adding Striking Runes to your handwraps, your Eidolon and your summoned creature(s) benefit.
Constricting Hold^SoM: Easy damage and it doesn’t require a Strike so you don’t care about Multiple Attack Penalty. If your Eidolon’s primary unarmed strike has the Grapple property, this is a great idea. Use your first Action to Grab something, then constrict it until it falls down.
Energy Resistance^SoM: If you’re going to invest in Dual Energy Heart, you absolutely want this so that you can exceed the damage resistance provided by Reinforce Eidolon.
Hulking Size^SoM: More size and reach makes Eidolon’s Reaction much more effective. Excellent if you want your Eidolon to serve as your party’s Defender.
Magical Adept^SoM: By this level, these low-level spells are largely only useful as buffs, but that doesn’t necessarily make them bad. Considering the Summoner’s limited spellcasting options, this can add some additional magic options beyond telling your Eidolon to go eat someone.
Miniaturize^SoM: Very situational. There’s little real benefit to being Tiny compared to being Small.

10th Level

Burrowing Form^SoM: Burrowing allows you to bypass many obstacles unobserved, to hide underground between turns, and otherwise make yourself a problem.
Merciless Rend^SoM: Don’t expect this to be consistently useful. It would only be useful on turns when you already planned to make three Strikes, and even on those rare turns you can’t guarantee that you’ll get to use this.
Protective Bond^SoM: Situational by design, but area damage is common and it’s a huge problem for the summoner because you commonly apply the damage twice to your shared pool of hit points.
Pushing Attack^SoM: Hit an enemy with one Action, Shove them automatically with another Action, and now they’re likely out of melee reach when their turn starts, forcing them to spend an Action to Step or Stride instead of spending that Action to attack.
Transpose^SoM: Not always useful, but great insurance if you get dragged into melee. You can also combine this with things like Unfetter Eidolon to send your Eidolon to explore, then switch places with it when it reaches somewhere that you want to be. There’s no usage limitation beyond the Action cost.
Weighty Impact^SoM: Hit an enemy with one Action, Trip them automatically with your second, then use your Eidolon’s secondary attack (which is Agile) to attack the target while they’re Flat-Footed to maximize your likelihood to hit.

12th Level

Flexible Transmogrification^SoM: There aren’t many feats which work well with this that can’t be replaced by Evolution Surge. Dual Energy Heart is a notable exception, but I don’t know if that’s enough.
Grasping Limbs^SoM: Potentially useful in conjunction with Constricting Hold, but it may be more reliable to start with the Grab then go straight to constricting.
Link Focus^SoM: Focus spells are really good.
Summoner’s Call^SoM: Only situationally useful, and it doesn’t protect you in any way.
Towering Size^SoM: Excellent for the reach and the space it occupies, but a huge creature is hard to drag around so be careful about taking this unless you also have Shrink Down.

14th Level

Airborne Form^SoM: Flight is really good.
Resilient Shell^SoM: This will be consistently useful, but Reinforce Eidolon will provide more damage resistance and works against more damage types, so you don’t absolutely need this.
Share Eidolon Magic^SoM: You’re already a spellcaster, and if you’re investing in your Eidolon’s ability to cast spells, your Eidolon should cast those spells. If you want to cast more spells, take the multiclass dedication feats for bard or sorcerer.
Spell-Repelling Form^SoM: Not always useful, but useful often enough.

16th Level

Effortless Concentration^SoM: To get the most out of your limited spell slots, you want to cast spells with ongoing effects like summon spells. The ability to Sustain one of those spells for free each turn gives you a lot of room to do other things like summoning another creature.
Ever-Vigilant Senses^SoM: Not always useful, but useful enough to make a difference.
Trample^SoM: A good, consistent way to handle crowds, but it’s not worth the feat unless your eidolon is at least large, and being huge is preferred. Keep in mind that this will still provoke Reactions.

18th Level

Link Wellspring^SoM: Focus spells are really good. Summoners don’t get a lot of Focus Spell options, but if you’re getting a lot out of Eidolon’s Wrath, this is definitely worth the feat.
Magical Master^SoM: This is a lot of additional spellcasting.
True Transmogrification^SoM: It’s unlikely that you’ll want to do this often enough to justify such a high-level feat.

20th Level

Eternal Boost^SoM: Permanent +1 to AC and saves or permanent +8 to damage with Strikes. Not much nuance, but it’s consistently useful.
Legendary Summoner^SoM: A great improvement to a tactic that you’ve likely relied upon for a long time.
Twin Eidolon^SoM: If you’re built entirely around your Eidolon doing the work, this is great. However, it removed all of your normal Summoner things that you do in combat like casting spells (Boost Eidolon, etc.), so you might spend a couple combats burning through spell slots before you switch to this.

General Feats

Armor Proficiency^CRB: The Summoner gets no armor proficiency and your Unarmored Defense proficiency hits Expert at level 13 and stops. Taking Armor Proficiency to get light armor will at least match your Unarmored Defense for your whole career and reduces the amount of Dexterity you need to max out your AC from 20 to 16, which is much easier to achieve. Taking Armor Proficiency again will reduce your Dexterity needs to just 12, allowing you to put your boosts in other places. However, remember that the Summoner’s Reflex saves are poor, so some Dexterity is a good idea.
Shield Block^CRB: A good way to boost your durability, though it won’t help your Eidolon.
Toughness^CRB: 10+ hit points is great, but the Summoner’s armor options and proficiencies are terrible and your Eidolon’s aren’t much better, so you need as much HP as you can get.

Summoner Weapons

There is no circumstance under which you should be using a weapon. Summoners start at Trained and never improve past Expert. You need to invest in handwraps to enhance your Eidolon’s unarmed strikes, so also investing in a weapon is a massive cost that you simply cannot justify.

Learn some cantrips. Gouging Claw for melee and literally any ranged attack cantrip.

Summoner Armor

No armor proficiency unless you take a feat for it.

Summoner Focus Spells – Link Spells

Cantrips

Boost Eidolon^CRB: On a turn where your Eidolon is going to make numerous Strikes, this can result in a significant damage boost. But be sure to weigh the opportunity cost: could you do more damage with that same Action by casting a spell? Your options for single-Action damage spells are few and far between, so the answer is often “no”, but sometimes it makes more sense for you to use an offensive cantrip rather than boosting your Eidolon.
Reinforce Eidolon^CRB: 1 Action for +1 to all of your Eidolon’s defenses and damage resistance to all types of damage. Not flashy and the damage resistance will scale slowly, but it’s an easy way to spend an Action and it will pay off repeatedly over time.

1st-Level Spells

Evolution Surge^CRB: At low levels, this covers a variety of capabilities also covered by low-level evolution feats like Amphiibous Form and Extended Senses. Many of these feats are only situationally useful, so having their benefits available temporarily via focus spell is a great way to cover multiple cases with a single resource.
As you gain levels, you add the ability to increase your Eidolon’s size, replicating the Hulking/Towering Size feats, or to give your Eidolon a climb or fly speed. This keeps Evolution Surge consistently useful and versatile for your whole career.
Extend Boost^CRB: The effects are fine and can save you several Actions over the course of a single combat. The problem is the skill check. You’re making either an Intelligence-based check or a Wisdom-based check, and since neither of those are high-importance ability scores for the Summoner, it will be difficult to consistently succeed on the skill check for this. Failure won’t eat your Focus Point so you can retry every turn, but Critical Failure will consume the Focus Point so this will always be a frustrating gamble. It’s great when it works, but it’s hard to make this work consistently without a ton of investment that’s likely better spent elsewhere.
Unfetter Eidolon^CRB: If you want to send your Eidolon to scout an area, to deal with traps, or generally to do something too dangerous for you to handle on your own, this can help. Unfortunately, the duration is short. You can re-cast this to get up to three minutes (assuming that your Focus Pool is 3 points), but situations where this is useful aren’t a guarantee. If you combine this with Reactive Dismissal, you can send your Eidolon to safely scout for danger and unmanifest it to mitigate damage which would be dealt to your shared pool of hit points, allowing your Eidolon to trigger traps while you’re at a very safe distance.

2nd-Level Spells

Lifelink Surge^CRB: Not a ton of healing, but it’s enough to get rid of persistent Bleed damage, and it’s easy healing outside of combat that will work faster than Medicine checks. Keep in mind that if you hit 0 hit points, your Eidolon unmanifests and the Fast Healing goes away, so you can’t use this to preventatively heal yourself from 0 hp.

3rd-Level Spells

Eidolon’s Wrath^CRB: A good amount of damage, good scaling, and a good AOE centered on your Eidolon. You don’t get to change the damage type, so I strongly recommend sonic damage because resistance to it is so rare. This is basically a fireball emanating from your Eidolon as a Focus Spell.

Archetypes

Bard / Sorcerer: More Charisma-based spellcasting.
Champion: One feat to get heavy armor proficiency.

Summoner Handbook: PF2 Class Guide – RPGBOT