Stuff of Nightmares

Some Warp entities are so terribly powerful that the willpower perpetuating their bodies in reality is almost impossible to break or disrupt.
Such creatures count as having the Undying trait, and are completely immune to most environmental hazards, Blood Loss, and Stunning.
They also ignore any Critical Effect other than one that would destroy them outright, unless it was caused by a psychic power, force weapon, or holy attack.