Discorporate (feat)

[UNDEAD FEAT]

Benefit: You do not require a physical form. You become incoporeal for a number of rounds equal to your Hit Dice or your Character Level, whichever is higher as a free action. Your equipment and any creatures you entirely enclose are likewise momentarily out of phase with the material world. These rounds may be split into as many different uses as the the player would like.

Prerequisites: no Constitution score, must not be mindless

from Secret College of Necromancy