Meld into Eidolon Feat 1
Source Pathfinder Secrets of Magic
Your physical form can combine with that of your eidolon, granting benefits but limiting your capabilities.
You Manifest your Eidolon, but instead of summoning it into an adjacent open space, you become it. While Manifested in this way, you use its statistics, and you can't act except to direct it to use Manifest an Eidolon to unmanifest it.
Since you can't act, you can't Cast Spells, activate or benefit from magic items that normally benefit you and not your eidolon, perform actions that have the tandem trait, or use other abilities that require you, and not the eidolon, to act.
You can't be separately targeted while you are melded into it. When you reach 0 HP, your eidolon unmanifests, leaving your body behind, unconscious and dying.
Traits
Anything that doesn't list another rarity trait (uncommon, rare, or unique) automatically has the common trait. This rarity indicates that an ability, item, or spell is available to all players who meet the prerequisites for it. A creature of this rarity is generally known and can be summoned with the appropriate summon spell.
SummonerThis indicates abilities from the Summoner class.