Alignment: Neutral.
Base Evolutions: At 1st level, astral eidolons gain immunity to aging as well as a +4 bonus on saving throws against curses, diseases, and poisons. A summoner’s class level is halved for the purpose of determining the rate at which his astral eidolon’s Strength and Dexterity increase.
At 4th level, astral eidolons gain the ability to augment their masters’ summoning abilities three times per day. To do so, the astral eidolon must ready an action to meld with a summoned creature. The summoner can use his summon monster spell-like ability or cast a summon monster spell while the astral eidolon is summoned and readied to activate this ability. The eidolon physically melds with one summoned creature as it appears, during which time the eidolon cannot be harmed or take actions of its own except to end the effect as a standard action. The eidolon must be adjacent to or share the space where the summoned creature will appear. The effect ends either when the spell ends, when the summoned creature is slain or dismissed, or when either the summoner or eidolon ends the effect as a standard action, after which the summoned creature disappears and the eidolon appears in the creature’s space and is staggered until the beginning of the summoner’s next turn.
When melded with a summoned creature, the eidolon grants the summoned creature one or more evolutions the eidolon has (maximum 1 point worth of evolutions for every 3 Hit Dice the eidolon has) and a number of temporary hit points equal to 1d8 plus the eidolon’s number of Hit Dice. The summoned creature must conform to any limitations of the evolution (for example, it must have wings in order to gain the wing buffet evolution). Furthermore, the summoned creature cannot gain more than one natural attack in this way, though it can replace the damage of its natural weapons with that dealt by the evolution, provided the natural weapons are similar. For effects dependent on Hit Dice, use the eidolon’s Hit Dice.
At 8th level, astral eidolons gain the flight evolution (using magic) with a speed equal to their base speed.
At 12th level, astral eidolons gain the ability to augment their master’s summoning two additional times per day. When the eidolon melds with a summoned creature, that creature also gains the eidolon’s evasion and devotion abilities.
At 16th level, astral eidolons gain immunity to curses, diseases, and poisons. They also increase by 50% the number of evolution points their summoners can divert using the aspect and greater aspect abilities. If the summoner lacks the aspect ability, he gains this ability but can divert only 1 evolution point. The summoner no longer takes penalties to his ability scores for aging, cannot be magically aged, and does not age retroactively when leaving a plane with the timeless planar trait. Ability score bonuses from age still accrue, and the summoner still dies of old age when his time is up.
At 20th level, astral eidolons can simultaneously meld with each creature summoned by the summoner’s summon monster spell-like ability or summon monster spells, and the eidolon does not reappear automatically until each of the creatures is slain. Alternatively, the eidolon can meld with one summoned creature without disappearing, though the eidolon is staggered until the effect ends.
