You may score critical hits against creatures that are normally unaffected by critical hits.
Prerequisite: Base attack bonus +2 or better.
Benefit: When you roll a threat against a creature normally unaffected by critical hits (such as a construct, ooze, or undead), you may check for a critical hit and deal the increased damage if the threat is confirmed. Creatures unaffected by massive damage are still unaffected by massive damage resulting from a critical hit. This is a supernatural ability.