Spiteful Purge
Whenever a being that is affected by a temporary beneficial effect deals hitpoint damage (excluding nonlethal damage) to you, you can spend an immediate action in order to cause the duration of that effect to expire prematurely.
Note: This hex can only be learned by a corrupted soul.
FAQ
Q: If the being that dealt damage to me is affected by multiple temporary beneficial effects, how would I determine which one expires prematurely?
A: You would assign a number to each of those temporary beneficial effects and then roll a die of appropriate size in order to determine which one expires prematurely (for example, if they are affected by three temporary beneficial effects, you would roll a d3).