Whirling divine energy promises swift retribution if one of your foe's companions attacks you.

At-Will   ✦     Divine, Radiant, Weapon
Standard Action      Melee weapon

Target: One creature

Attack: Wisdom vs. AC

Hit: 1[W] + Wisdom modifier damage. The first time an enemy other than the target hits or misses you before the end of your next turn, the target takes radiant damage equal to your Intelligence modifier.
Level 21: 2[W] + Wisdom modifier damage.

Published in Player's Handbook 2, page(s) 35.