Gruesome Strike
FEAT 12 1 action
champion's reaction that grants extra damage with your Strikes (including the desecration, iniquity, and obedience causes)
Your Strikes currently deal extra damage from your champion's reaction.
Make a Strike against the creature that triggered your champion's reaction. If you hit, double the extra damage the target takes from your reaction, and the target must succeed at a Fortitude save against your class DC or be Drained 1. Regardless of the result, the creature is temporarily immune to your Gruesome Strike for 24 hours.
Pathfinder Player Core 2ORC