EIDOLONIST

A half elf clad in chain-mail fights desperately against a group of orcs, but she is hopelessly outnumbered. The horde closes in around her, grinning madly. She mimics their grin and whistles loudly. A centipede-like creature swoops under her and lifts her into the sky, the buzzing of its wings mixing with her whoops of laughter and the frustrated cries of the orcs below.

A human stands watch around a campfire deep in the woods, arms crossed, one red eye staring out into the darkness. Behind him, a contraption of scrap armor vaguely resembling a wolfhound sits by the lookout's feet and whines. The human smiles, and an iron hand reaches out from underneath the cloak to scratch the metallic dog's head behind the ears.

A man-shaped aberration weakly raises a hand to ward off the toxic breath of the dragon. From across the treasure hoard, an elf holds up her hand and whispers a few words. With renewed strength, the cephalopodic humanoid grabs the dragon with all eight of its limbs and rips its lower jaw clean off.

Whether they wish for companionship, a fighter, or simply a willing test subject, eidolonists are among those select few who have unlocked the mysteries of life itself.

Artificial Life

The exact nature of eidolons is a subject rife with misconceptions and old wive's tales, but at its simplest form, eidolons are empty shells. Their bodies are sculpted from clay, leaves, iron, or other materials, and imbued with a spellcaster's full arcane might. At the end of the ritual, the spellcaster is completely drained of their ability to access the Weave, and the golem is imbued with a consciousness that almost approaches sentience, though it is still bound to the will of its creator. The large amount of magical energy contained inside the eidolon quickly makes it mutate beyond the form originally sculpted for it. These mutations very rarely harm the creature, though the sight of a many-tentacled abomination writhing its way through the town square tends to attract undue attention from commoners, and so most eidolonists will keep their eidolon safely hidden in a custom-built demiplane.

Creating an Eidolonist

As you create your eidolonist, think about how they acquired the knowledge to create one in the first place. Did they research it on their own? Was there an ancient tablet that they deciphered that revealed the long-lost secrets of eidolomancy? Or were they part of a wizarding school where such knowledge is easily available? And why did they chose to give up their magical power? Did they want to research the nature of chaos itself? Or were they unaware that the procedure would take away their magic?

Quick Build

You can make an eidolonist by following these suggestions. First, make Charisma your highest score, followed by Constitution. Make Dexterity or Strength your next highest if you plan to take the Commander relationship, or Intelligence if you plan to take the Summoner relationshp. For your eidolon, chose the Biped form and the Abberation type.

The Eidolonist

Level	Proficiency Bonus	Features	Evolutions Gained
1st	+2	Summon Eidolon	—
2nd	+2	Chaos Burst, Evolutions	2
3rd	+2	Relationship	2
4th	+2	Ability Score Improvement	2
5th	+3	Extra Hit	3
6th	+3	Ability Score Improvement, Master Tactician	3
7th	+3	Relationship Feature	4
8th	+3	Ability Score Improvement	4
9th	+4	Life Tap	5
10th	+4	Frightful Presence	5
11th	+4	Chaos Burst Improvement	5
12th	+4	Ability Score Improvement	6
13th	+5	Timeless Exterior	6
14th	+5	Ability Score Improvement	6
15th	+5	Relationship, Major Evolution	7
16th	+5	Ability Score Improvement	7
17th	+6	Extra Hit (2)	7
18th	+6	Life Tap Improvement	8
19th	+6	Ability Score Improvement	8
20th	+6	Relationship Feature	8

Class Features

As an eidolonist, you gain the following class features.

Hit Points

Hit Dice: 1d6 per eidolonist level
Hit Points at 1st Level: 6 + your Constitution modifier
Hit Points at Higher Levels: 1d6 (or 4 ) + your Constitution modifier per eidolonist level after 1st

Proficiencies

Armor: Light armor
Weapons:Daggers, darts, slings, quarterstaffs, light crossbows
Tools: None

Saving Throws: Charisma, Wisdom
Skills: Choose two from Animal Handling, Arcana, Deception, History, Insight, Investigation, Medicine, Perception and Persuasion,

Equipment

You may start with either 3d4x10 gp or the following equipment, in addition to the equipment granted by your background:

(a) a scholar's pack or (b) an explorer's pack
(a) two daggers or (b) a quarterstaff
leather armor
a statuette of your eidolon, worth 5 GP

Summon Eidolon

You have sculpted a piece of your own soul and inserted it into the body of a creature you have made. This being is called an eidolon, and it can take the form of a biped (which walks on two legs like a humanoid), a quadruped (which runs on four legs like a dog), or a serpent (which slithers like a snake). Your eidolon can communicate telepathically with you if you are within 100 feet of it, and it knows any languages you know but cannot speak.

Your eidolon obeys your commands as best as it can. It takes its turn on your initiative, though it doesn't take an action unless you command it to. On your turn, you can mentally command your eidolon where to move (no action required by you). You can use your action to mentally command it to take the Attack, Dash, Disengage, Dodge, or Help action, or you can use your action to see through your eidolon's senses, taking advantage of any special senses it possesses until the start of your next turn. While observing through your eidolon's senses, you are blind to your own surroundings.

As an action, you can dismiss your eidolon into a pocket dimension. If it is inside this pocket dimension, you can use your action to make it reappear in any unoccupied space within 30 feet of you. Your eidolon can be banished to this dimension, but spells such as dispel magic or antimagic field will not cause it to be sent back. If your eidolon dies, you can use your reaction to dismiss it back to the pocket dimension to regenerate. At the end of your next long rest, you can summon it back with all of its hit points restored. If you are knocked unconscious, your eidolon immediately returns to its pocket dimension. If you die, both the pocket dimension and your eidolon are immediately destroyed. If your eidolon is completely destroyed, you may recreate it in a one-day ritual that requires a 5 GP statuette of your eidolon (this statuette is not consumed by the ritual).

Eidolon Creation

Use the standard array method to determine your eidolon's stats; however, none of its stats can be higher than your Charisma score. Its size is Medium, its speed is 20 feet, its armor class is equal to 10 plus its Dexterity modifier, and its proficiency bonus is equal to 2 plus (your eidolonist level + 1)/4, rounded down. Its has one d10 hit dice for each level of eidolonist you take, and its hit point maximum equals 10 + its Constitution modifier, plus 1d10 (or 5) + its Constitution modifier for each eidolonist level after 1st. It has an unarmed strike that deals 1d6 + its Strength modifier bludgeoning, piercing, or slashing damage (your choice).

Its appearance and general shape is up to you; however, you do not have enough control to make it appear like a specific creature or person. Anyone who looks at your eidolon will be able to tell that it is not a naturally-occurring creature.

The form you gave your eidolon changes determines its speed, skill and saving throw proficiencies, and gives it a bonus evolution.

Biped

Saving Throw Proficiencies: Constitution, Charisma
Skill Proficiencies: One from Athletics, Acrobatics, Stealth, Insight, Perception, Survival, and Intimidation.
Speed: 30 ft
Bonus Evolution: Grasping Limbs

Quadruped

Saving Throw Proficiencies: Strength, Wisdom
Skill Proficiencies: One from Athletics, Acrobatics, Stealth, Insight, Perception, Survival, and Intimidation.
Speed: 40 ft
Bonus Evolution: Pounce

Serpentine

Saving Throw Proficiencies: Dexterity, Intelligence
Speed: 20 ft
Skill Proficiencies: Two from Athletics, Acrobatics, Stealth, Insight, Perception, Survival, and Intimidation.
Bonus Evolution: Chose either Darksight or Tremorsense

In addition to chosing a form, you can select an origin for your eidolon. Your eidolon is considered a creature of that type, and it gains an additional benefit depending on its type.

Fey - Your eidolon cannot be Charmed, and its Dexterity score increases by 1.

Construct - Your eidolon cannot be Poisoned, and its Constitution score increases by 1.

Aberration - Your eidolon cannot be Frightened, and its Strength score increases by 1.

Fiend - Chose either fire, cold, or lightning damage. Your eidolon's infernal heritage gives it resistance to that damage type, and its Intelligence score increases by 1.

Monstrosity - Chose either bludgeoning, piercing, or slashing damage. Your eidolon's thick hide gives it resistance to that damage type, and its Wisdom score increases by 1.

Celestial - Chose either radiant or necrotic damage. Your eidolon's divine essence gives it resistance to that damage type, and its Charisma score increases by 1.

Chaos Surge

Starting at 2nd level, your eidolon struggles to contain all of the mutagenic essence in its body. Whenever it rolls a 1 on an attack roll, saving throw, or skill check, the DM can have you roll on the Wild Magic Surge table in the PHB, applying the effect to the eidolon instead of you.

Starting at 11th level, whenever you roll on the Wild Magic Surge table, you can roll twice and use either number.

Evolution

Unlike undead corpses or conjured beings, eidolons are fluid and ever-changing. At 2nd level, your eidolon gains two evolutions of your choice. Your evolution options are detailed at the end of the class description. When you gain certain eidolonist levels, you gain additional evolutions of your choice, as shown in the Evolutions Gained column of the Warlock table.

Additionally, when you gain a level in this class, you can choose one of the evolutions you know and replace it with another evolution that you could learn at that level. You cannot replace the bonus evolution your eidolon receives from its form.

Relationship

At 3rd level, you chose a relationship that determines how you interact with your eidolon and what your eidolon means to you. Chose either the Commander, the Researcher, or the Summoner. Your choice of relationship grants you additional features at 7th, 15th, and 20th level.

Ability Score Improvement

When you reach 4th level, and again at 6th, 8th, 12th, 14th, 16th, and 19th level, you can increase one of you or your eidolon's ability scores by 2, you can increase two of you you or your eidolon's ability scores by 1, or you can increase one of your ability scores by 1 and one of your eidolon's ability scores by 1. As normal, you can't increase an ability score above 20 using this feature, and you cannot increase an ability score of your eidolon above your Charisma score.

Extra Hit

When you reach 5th level, your eidolon can attack twice instead of once when you command it to take the Attack action. This increases to three times at 17th level.

Master Tactician

Starting at 6th level, on any of your turns when your eidolon doesn't attack, you can use a bonus action to command your eidolon to take the Dash, Disengage, or Dodge action.

Life Tap

Starting at 9th level, the piece of you contained within your eidolon can sap some of your life force to sustain your eidolon, or vice versa. As an action when you are touching your eidolon, you can sacrifice a number of your current hit points up to your Charisma score. Your eidolon is healed by half the amount you sacrificed. You can also order your eidolon to use its action to touch you or another creature and sacrifice hit points up to your Charisma score, healing the target by half the amount sacrificed. Whenever you use this feature, roll a d20 to see if you activate your Chaos Rush feature.

At 18th level, the recipient of this feature heals for the full amount of hit points sacrificed.

Frightful Presence

At 10th level, your eidolon's presence is terrifying to behold. You and your allies have advantage on all Intimidation checks when within 30 feet of your eidolon.

Timeless Exterior

Exposure to your eidolon's chaotic power has begun to change your body. At 13th level, you no longer appear to age. However, for every year that passes, your body ages 5 years.

Relationships

Eidolonists have many different motivations for giving up a piece of their soul to form this new being. For some, their eidolon is like a beloved pet. Others use them for fights. And some simply prefer the convenience of having a willing test subject for their research.

Commander

Whereas other eidolonists would send their creations into battle from afar and cower behind a rock, you see yours as the most faithful soldier in the world. You know where and when to send it to strike fear into the hearts of your enemies, and you aren't afraid to jump in and lead from the front when the situations demands it.

Combat Training

Starting at 3rd level, you gain proficiency in medium armor, shields, shortbows, and any simple or martial melee weapon that does not have the heavy or two-handed property.

Tactics Mastery

Also at 3rd, you have gained an understanding of the flow of battle and how to manipulate it to your advantage. You gain four superiority dice, which are d6s. In addition, chose three maneuvers from the Battlemaster list. Either you or your eidolon may execute these maneuvers. You gain another maneuver at 7th, 15th, and 20th level. You use your eidolon's Strength score to set the save DC for these maneuvers.

Improved Dice

At 7th level, your dice become d8s. At 20th level, they become d10s

Split Strike

Starting at 7th level, when you take the Attack action on your turn, you can order your eidolon to make one unarmed attack with its action. When you reach 20th level and take the Attack action, your eidolon can make two unarmed attacks with its action.

Adrenaline Rush

Starting at 15th level, when your eidolon activates its Chaos Rush feature and you have no superiority dice remaining, you regain one superiority die.

Sentience

Starting at 20th level, you can temporarily imbue your partner with a degree of independent thought. For one minute, your eidolon rolls initiative separately and acts on its own turn. You may issue simple commands to your eidolon, such as, "Kill that dragon," "Help that fighter," or "If any cultists escape, pursue them," without using an action. Your eidolon will obey your commands as best as it can, taking whatever tactics it deems necessary to accomplish its task. Once the minute ends and your eidolon returns to your control, you cannot use this feature again until you complete a long rest.

Researcher

Whereas other eidolonists view the evolutions their creations undergo as a side effect of the magic used to create them, you see them as an opportunity to learn more about the mechanisms of magic and life itself. After all, your eidolon is technically you, in a sense; what better test subject is there than yourself?

Horrific Form

At 3rd level, you have learned how to take some of your eidolon's mutatable essence and apply it to yourself. Whenever your eidolon gains an evolution, you may steal it and apply it to your body instead. If an evolution has a prerequisite, you cannot use it on yourself.

Poison Resistance

Starting at 7th level, constant exposure to the mutagenic forces of your eidolon has vaccinated you from the words of their effects. You resist poison damage, and have advantage on saves against becoming poisoned.

Elemental Rush

Starting at 15th level, when your eidolon activates its Chaos Rush feature, you can chose to convert some of that magical energy into a blast of raw elemental power. Chose fire, cold, lightning, or thunder. Every creature within 30 feet of it must make a Dexterity saving throw (DC = 8 + your eidolon's proficiency bonus + your eidolon's Charisma modifier), taking 5d6 damage of that type on a failed save and half damage on a successful save. Roll twice on the Wild Magic Surge table. The DM choses which number to use.

DNA Splice

At 20th level, your genome and the genome of your eidolon have become intertwined and almost indistinguishable. As an action when your eidolon is within 5 feet of you, you can merge with it for one minute, becoming a single creature with the following properties:

The creature's current hit points and hit point maximum is the sum of you and your eidolon's current hit points and hit point maximums, respectively.
The creature has your base speed, proficiency bonus, and ability scores, unless your eidolon's is higher.
The equipment you and your eidolon were using either falls to the ground or merges into it. Merged equipment can't be used.
The creature behaves as an eidolon with all of the evolutions your eidolon has, plus all of the evolutions you have from the Horrific Form feature. It also has access to any of your class features, racial features, or bonus feats.

After one minute, the merging ends and you are ejected to a space within five feet of the merged creature. If there is no space within five feet of you to reappear, you are shunted to the closest available space and take 2d6 force damage for every five feet you traveled. Your eidolon occupies the space of the merged creature. Any damage the merged creature took is split evenly between you and your eidolon. You cannot use this feature again until you complete a long rest.

Summoner

Whereas most eidolonists see the loss of their magical power as a fair trade-off for the combat potential and versatility of an eidolon, you beg to differ. Why can't you continue to practice the art which led you to become an eidolonist? With the use of transmutation spells to empower your eidolon and conjuration spells to control the battlefield, you can make you and your partner almost unstoppable.

Summoner Spellcasting

			—Spell Slots per Spell Level—
Eidolonist Level	Cantrips Known	Spells Known	1st	2nd	3rd	4th
3rd	2	3	2	—	—	—
4th	2	4	3	—	—	—
5th	2	4	3	—	—	—
6th	2	4	3	—	—	—
7th	2	5	4	2	—	—
8th	2	6	4	2	—	—
9th	2	6	4	2	—	—
10th	3	7	4	3	—	—
11th	3	8	4	3	—	—
12th	3	8	4	3	—	—
13th	3	9	4	3	2	—
14th	3	10	4	3	2	—
15th	3	10	4	3	2	—
16th	3	11	4	3	3	—
17th	3	11	4	3	3	—
18th	3	11	4	3	3	—
19th	3	12	4	3	3	1
20th	3	13	4	3	3	1

Spellcasting

When you reach third level, you regain some of the magic you lost when you became an eidolonist. See chapter 10 of the PHB for the general rules of spellcasting and chapter 11 for the wizard spell list.

Cantrips. You know two wizard cantrips of your choice. You learn another wizard cantrip of your choice at 10th level.

Spell Slots The Eidolonist Spellcasting table shows you how many spell slots you have to cast your spells of 1st level and higher. To cast one of these spells, you must expend a slot of the spell's level or higher. You regain all expended spell slots when you finish a long rest.

Spells Known of 1st-Level and Higher. You know three 1st-level wizard spells of your choice, two of which must come from the conjuration or transmutation schools of magic.

The Spells Known column of the Eidolonist Spellcasting table shows you when you learn more wizard spells of 1st level or higher. Each of these spells must be a conjuration or transmutation spell of your choice, and must be of a level for which you have spell slots. For instance, when you reach 7th level, you can learn one spell of 1st or 2nd level.

The spells you learn at 8th, 14th, and 20th level can come from any school of magic.

Whenever you gain a level in this class, you can replace one of the wizard spells you know with another spell of your choice from the wizard spell list. The new spell must be of a level for which you have spell slots, and it must be an enchantment or transmutation spell, unless you're replacing the spell you gained at 8th, 14th, or 20th level.

Spellcasting ability. Intelligence is your spellcasting ability for your wizard spells, since you learn your spells through dedicated study and memorization. You use your Intelligence whenever a spell refers to your spellcasting ability. In addition, you use your Intelligence modifier when setting the saving throw DC for a wizard spell you cast and when making an attack roll with one.

Spell save DC = 8 + your proficiency bonus + your Intelligence modifier

Spell attack modifier = your proficiency bonus + your Intelligence modifier

Lightened Load

At 7th level, you've learned how to use stretch your magic more efficiently. Any time you cast a transmutation spell that affects one or more willing creatures, you can affect one additional creature.

Arcana Rush

Starting at 15th level, when your eidolon activates its Chaos Rush feature, roll a d3. You regain one spent spell slot of that level, or the next lowest if all of your slots of that level are still available.

At 20th level, you can roll a d4 for this feature.

Mirror Eidolon

At 20th level, your mastery of magic has grown to the point where you can perfectly mimic your eidolon and swap places with it at will. For one minute, you can magically disguise yourself as your eidolon, becoming indistinguishable from it. Each time a creature targets you or your eidolon with an attack during the duration, you can chose to swap positions with your eidolon. Roll a d20; if you roll 10 or lower, the attack hits its intended target. If you roll 11 or higher, you switch locations with your eidolon, and the damage is dealt to the one not targeted. You must be within 100 feet and be able to see your eidolon to swap places with it. A creature that can see through illusion magic is not fooled by the illusion, though this does not prevent you from swapping places with your eidolon. Effects that prevent you or your eidolon from teleporting, such as dimensional shackles, prevent you from swapping placings but do not affect your disguise. Once the illusion is dispelled, you cannot use this feature again until you finish a long rest.

Evolutions

GRASPING LIMBS

Your eidolon grows clawed hands or dexterous tendrils capable of manipulating objects. It can pick up or carry heavy objects without assistance.

AMBULATORY LIMBS

Your eidolon sprouts a leg or tentacle ending in a foot, hoof, or pointed claw. Its speed increases by 10 feet.

SKILL PROFICIENCY

Chose one skill from Athletics, Acrobatics, Stealth, Insight, Perception, Survival, and Intimidation. Your eidolon is now proficient in checks involved with that skill.

CLIMBING

Your eidolon gains the ability to cling onto almost any surface like a suction cup. In addition, it gains a climbing speed equal to its base speed, and can climb up smooth surfaces with no obvious handholds. To pull an eidolon off of a surface it is climbing requires succeeding on a Strength check contested by the eidolon's Strength check.

AQUATIC

Your eidolon is just as comfortable in the water as it is on land. It gains a swim speed equal to its base speed.

SCENT

Your eidolon's olfactory organs have grown more efficient, letting it detect hidden enemies or track quarry through thick underbrush. It has advantage on any checks that involve smell.

SLIPPERY

Your eidolon has advantage on any check to escape being restrained.

TOUGH SKIN

Prerequisite: 7th level

Your eidolon's skin has grown tougher. Its AC is now equal to 13 + its Dexterity modifier.

TOOL USAGE

Prerequisite: 3rd level, Grasping Limbs

Your eidolon's coordination has improved to the point where it can swing a sword or fire a crossbow. Your eidolon becomes proficient with any melee weapon you are proficient with.

ARMOR USAGE

Prerequisite: 3rd level, Commander relationship

Your eidolon has become tame enough to allow you to fit armor to it. It now has proficiency in light and medium armor, though the armor may need to be re-tailored to fit it as it evolves.

POISON NEEDLE

Prerequisite: 3rd level, Researcher relationship, Bite or Tail

Your eidolon grows a gland capable of producing a venomous substance. Chose one bite or tail attack. When your eidolon hits a creature with that attack, the creature must make a Constitution saving throw (DC 8 + your eidolon's proficiency bonus + its Charisma modifier) or take 1d4 additional poison damage.

TAIL SPIKES

Prerequisite: 15th level, Researcher relationship, Tail

Inspired by the biology of the manticore, your eidolon's tail becomes covered in a number of spiny, detachable protrusions equal to its Charisma score. Whenever your eidolon makes a tail attack, it may fire a number of spikes up to its Charisma modifier at a single creature. Treat the spikes as a ranged weapon with a range of 30/60 feet. On a hit, they deal 1 + your eidolon's Dexterity modifier of piercing damage. Any features that modify your eidolon's tail attack, such as Poison Needle, also affect this evolution. Once the eidolon has fired all of its needles, it must complete a short or long rest before it can do so again.

KINDRED SPIRIT

Prerequisite: 3rd level, Summoner relationship

Your eidolon's essence becomes closely intertwined with your own, becoming more like a wizard's familiar than anything else. Whenever you cast a spell with a range of touch or self, your eidolon can use its action to deliver or receive the spell if it is within 100 feet of you. If the spell requires an attack roll, you use your own spell attack modifier for the roll.

INNATE MAGIC

Prerequisite: 7th level, Summoner relationship

Your eidolon has begun to absorb some of the magic you keep slinging around. Chose one cantrip with a casting time of one action from the wizard spell list. It can now cast that cantrip using its Intelligence. Once it casts that cantrip a number of times equal to its Intelligence modifier, it must finish a long rest before it can do so again.

TELEPORTATION

Prerequisite: 15th level, Summoner Relationship

Your eidolon can innately cast dimension door as a 4th level spell, targeting only itself or itself and you if you are within 5 feet of it. It must finish a long rest before it can do so again.

AMPHIBIOUS

Your eidolon develops gills, slimy skin, or some other adaptation that allows it to breath underwater. Taking this evolution does not mean that your eidolon is unable to breath on land.

BITE

Your eidolon's gnashing molars, needle-like teeth, or blade-sized mandibles become sturdy enough to deal damage. Once per turn when your eidolon takes the Attack action, it can make a bite attack instead of an unarmed strike. The eidolon's bite is treated as an unarmed strike, and the target must make a Strength (Athletics) check or be grappled.

TAIL SWIPE

Your eidolon gains a thick tentacle, tufted tail, or chitinous extension to its body. Once per turn when your eidolon takes the Attack action, it can make a tail swipe attack instead of an unarmed strike. The eidolon's tail swipe is treated as an unarmed strike with the Reach property.

POUNCE

Your eidolon has learned how to strike like a panther. If your eidolon moves at least 20 feet in a straight line toward a creature right before hitting it with an attack, the target must suceed on a Strength check (DC 8 + the eidolon's proficiency bonus + its Strength modifier) or be knocked prone. If the target is prone, the eidolon can make one unarmed strike as a bonus action.

DARKVISION

Your eidolon's eyes, optical sensors, or other visual sensory organs have grown more accustomed to low-light conditions. Your eidolon now has darkvision to a range of 60 feet. It cannot distinguish colors, only shades of grey.

TREMORSENSE

Your eidolon's feet, cillia, or antennae have grown more sensitive to the subtle movement of the earth beneath it. It gains tremorsense to a range of 30 feet.

WEBBING

Your eidolon gains a gland in its mouth, near its wrist, or near its rectal cavity that can produce a mass of sticky threads. It can cast web at its lowest level without providing somatic or material components. The spell uses your eidolon's Charisma as the spellcasting modifier, and does not require concentration from either you or your eidolon. After 1 hour, the webs become brittle and lose their stickiness. As an action, your eidolon can completely consume the webs. Once your eidolon uses this ability, it cannot do so again until it completes a short or long rest.

If your eidolon has the Climb evolution, it is not affected by its own webs.

STEALTH

Your eidolon gains color-changing skin, pheremones of non-detection, or simply becomes better at moving silently. It now has advantage on any check to avoid being noticed.

FLIGHT

Prerequisite: 12th level

Your eidolon gains feathers, leathery flaps, or chitionous wings that allow it to soar through the air. It gains a flying speed of twice its base speed.

ENLARGE

Prerequisite: 9th level

Rather than expend its evolutionary energy on modifying or acquiring new appendages or organs, your eidolon uses it to engorge itself. It is now a Large creature instead of a Medium one, and its unarmed attacks deal 1d8 damage.

REDUCE

Prerequisite: 9th level

Rather than expend its evolutionary energy modifying or acquiring new appendages or organs, your eidolon uses it to expel mass from its body. It is now a Small creature instead of a Medium one, and its unarmed attacks now deal 1d4 damage.

EXPERTISE

Prerequisite: 7th level

Your eidolon has become master through constant repetition and practice. Chose one of its skill proficiencies. Its proficiency bonus is doubled for any check it makes using that skill.

FAST REPAIRING

Prerequisite: 15th level

Your eidolon's cells have become more adept at absorbing the healing essence of the pocket dimension you store it in. While it is in that pocket dimension, it regains 1 hit point at the start of each of your turns, or ten hit points every minute outside of combat.

BURROWING

Your eidolon's hands, claws, or feet grow powerful enough to force their way through tough soil, giving it a burrow speed of half its move speed. The eidolon cannot dig through solid rock or metal. It can chose to pass without leaving any trace of its presence, or it can leave a hole wide enough for a creature the same size as it to move through as if it was difficult terrain. Creatures at least one size smaller than your eidolon may move through the tunnel unimpeded.

Note 1

Eidolonists use their innate magic and willpower to command and control their eidolon. As such, any humanoid capable of becoming a wizard, warlock, or sorcerer can become an eidolonist. Sorcerers in particular make good eidolonists because they have such a large capacity to work magic to begin with.

In campaign settings that restrict some class options to certain races, any race or subrace that can produce arcane casters - especially sorcerers - can also produce eidolonists (though you should always talk to your DM before creating a homebrew character).

Note 2

Though eidolons cannot use weapons or wear armor unless their eidolonist takes the Commander relationship, they are still capable of using magic items such as potions, rings, or other wondrous items. However, since they cannot speak, they cannot use any magic items that are activated by speaking a command, such as Daern's Instant Fortress. If you are a DM and wish to restrict an eidolon's access to magical items, consider modifying your magic items to require speaking a phrase to activate.

Note 3

Using point buy or rolling for your eidolon's ability scores is discouraged because it can lead to you having poorer stats than your eidolon. If you still wish to roll, or if one of your eidolon's scores surpasses your Charisma score because of a magic item or other effect, you may use this alternate rule for controlling an eidolon more powerful than you are.

Unruly Eidolon. If one of your eidolon's ability scores is higher than your Charisma score, then at the start of each turn when you command your eidolon to move, you must make a Charisma saving throw against your eidolon's highest ability score. On a successful save, you can command your eidolon as normal. On a failed save, your eidolon goes out of control and attacks the nearest creature within 60 feet of it, including you. You are incapable of sending it back to its pocket dimension during this time. You can repeat the Charisma saving throw at the end of each of your turns, regaining control over it on a success. Otherwise, the effect ends after one minute, your eidolon drops to 0 hit points, or if your eidolon starts its turn and there are no creatures within 60 feet that it can see or hear.

Art source: http://liyart.deviantart.com/art/Summoner-366746490