Collapse Feat 1
Source Pathfinder Book of the Dead
Frequency once per 10 minutes
Trigger An enemy's Strike against you is a critical hit.
You collapse into a pile of bones, mitigating the worst of the damage you would have taken, and the triggering attack deals only the amount it would deal on a hit (typically full damage instead of double damage). Any other effects caused by a critical hit still occur. While collapsed, you're Flat-Footed and can't act except to Stand, which re-forms you into a skeleton in a standing position.
Traits
Anything that doesn't list another rarity trait (uncommon, rare, or unique) automatically has the common trait. This rarity indicates that an ability, item, or spell is available to all players who meet the prerequisites for it. A creature of this rarity is generally known and can be summoned with the appropriate summon spell.
SkeletonThis undead is made by animating a dead creature's skeleton with negative energy. An ability with this trait can be used or selected only by skeletons.