Coup de Grace

As a Full-Round Action, you can use a melee weapon to deliver a coup de grace (pronounced “coo day grahs”) to a Helpless opponent. You can also use a bow or crossbow, provided you are adjacent to the target.
You automatically hit and score a Critical Hit. If the defender survives the damage, they must make a Fortitude Save (DC 10 + damage dealt) or die. A rogue also gets their extra sneak attack damage against a helpless opponent when delivering a coup de grace.
Delivering a coup de grace provokes an Attack of Opportunity from threatening opponents.
You can’t deliver a coup de grace against a creature that is immune to critical hits. You can deliver a coup de grace against a creature with total Concealment, but doing this requires two consecutive full-round actions (one to “find” the creature once you’ve determined what square it’s in, and one to deliver the coup de grace).