Some evokers choose to summon a planar creature rather than an aspect of a primal or deity.
The evoker is an archetype of the summoner class.
At 1st level, an evoker has the ability to summon to his side a powerful outsider called an esper (see Eidolons for more info). The esper forms a link with the evoker, who, forever after, summons an aspect of the same creature. An esper has the same alignment as the evoker that calls it and can speak all of his languages. Espers are treated as summoned creatures, except that they are not sent back to their home plane until reduced to a number of negative hit points equal to or greater than their Constitution score. In addition, due to its tie to its evoker, an esper can touch and attack creatures warded by protection from evil and similar effects that prevent contact with summoned creatures.
An evoker can summon his esper in a ritual that takes 1 minute to perform. When summoned in this way, the esper hit points are unchanged from the last time it was summoned. The only exception to this is if the esper was slain, in which case it returns with half its normal hit points. The esper does not heal naturally. If the esper is sent back to its home plane due to death, it cannot be summoned again until the following day. The esper remains until dismissed by the evoker (a standard action). If the evoker is unconscious, asleep, or killed, his esper is immediately banished. The esper takes a form shaped by the evoker’s desires. The esper’s Hit Dice, saving throws, skills, feats, and abilities are tied to the evoker’s class level and increase as the evoker gains levels. In addition, each esper receives a pool of evolution points, based on the evoker’s level, which can be used to give the esper different abilities and powers. Whenever the evoker gains a level, he must decide how these points are spent, and they are set until he gains another level of evoker.
The esper’s physical appearance is up to the evoker, but it always appears as some sort of fantastical creature. This control is not fine enough to make the esper appear like a specific creature. The esper also bears a glowing rune that is identical to a rune that appears on the evoker’s forehead as long as the esper is summoned. While this rune can be hidden through mundane means, it cannot be concealed through magic that changes appearance. An evoker‘s esper counts as an avatar for the purposes of feats and class features.
This ability modifies and replaces avatar.
Mutate Esper (Su)
At 9th level, an evoker can change his esper’s evolutions as if he had gained a level. To mutate his esper, the evoker must perform an arcane ritual that requires 8 hours of uninterrupted concentration and costs 200 gil per summoner level in material components.
This ability replaces transposition.
Evolve Base Form (Su)
Starting at 15th level, whenever the evoker gains a level, he can change his esper’s base form to a new base form. Once chosen, this base form is set until the evoker gains another summoner level.
This ability replaces paragon summons.
Twin Esper (Su)
At 20th level, an evoker and his esper share a true connection. As a standard action, the evoker can assume the shape of his esper, copying all of its evolutions, form, and abilities. His Strength, Dexterity, and Constitution scores change to match the base scores of his esper. He can choose to have any gear that he carries become absorbed by his new form. Items with continuous effects continue to function while absorbed in this way. The evoker loses his natural attacks and all racial traits (except bonus feats, skills, and languages) in favor of the abilities granted by his esper’s evolutions. The evoker retains all of his class features. The evoker can keep this form for a number of minutes per day equal to his evoker level. This duration does not need to be consecutive, but it must be spent in 1-minute increments. The evoker can end this effect as a free action.
This ability modifies and replaces twin avatar.