The exarch Gartak betrayed the gods. He was cursed so that the next killing blow he landed on a foe caused him to die with the same wound.

Daily   ✦     Divine, Implement
Standard Action      Ranged 10

Target: One creature

Attack: Wisdom vs. Will

Hit: 5d6 + Wisdom modifier damage.

Effect: Whenever the target hits with an attack, the target takes 10 damage. This effect ends at the end of the target's turn if it has not attacked since the end of its last turn.

Published in Player's Handbook 2, page(s) 110.