Regeneration

Creatures with this extraordinary ability recover from wounds quickly and can even regrow or reattach severed body parts. Damage dealt to the creature is treated as nonlethal damage, and the creature automatically cures itself of nonlethal damage at a fixed rate per round, as given in the creature’s entry.

Certain attack forms, typically fire and acid, deal damage to the creature normally; that sort of damage doesn’t convert to nonlethal damage and so doesn’t go away. The creature’s description includes the details. A regenerating creature that has been rendered unconscious through nonlethal damage can be killed with a coup de grace. The attack cannot be of a type that automatically converts to nonlethal damage.

Creatures with regeneration can regrow lost portions of their bodies and can reattach severed limbs or body parts. Severed parts die if they are not reattached.

Regeneration does not restore hit points lost from starvation, thirst, or suffocation.

Attack forms that don’t deal hit point damage ignore regeneration.

An attack that can cause instant death only threatens the creature with death if it is delivered by weapons that deal it lethal damage.

A creature must have a Constitution score to have the regeneration ability.