You can use your undead nature to pull a classic ruse.
Prerequisites: Undead type
Benefit: When you use the Bluff or Knowledge (religion) skills to appear fully dead (as opposed to undead), you may do so as an immediate action. Add a +4 circumstance bonus to this check if you activated this ability in response to suffering damage. As usual, you fall prone and observing creatures must succeed at a Knowledge (religion) or Perception check with a DC equal to your check’s result to realize that you are not fully dead.
Normal: It takes a move action for an undead creature to appear fully dead using the Bluff or Knowledge (religion) skills.
Lords of the Night, © 2018, Dreamscarred Press, LLC; Author: Written by Anthony S. Altovilla and Patrick C., based on material by Owen K.C. Stephens