You have sworn that your enemy shall fall—and it will, by your or your ally's hand.

Encounter   ✦     Divine
Immediate Interrupt      Close burst 5

Trigger: You or an ally within 5 squares of you makes an opportunity attack against your oath of enmity target

Effect: The opportunity attack deals 1[W] extra damage if it's a weapon attack, or 1d8 extra damage if it is not a weapon attack.

Update (8/17/2012)
Changed in July 2012 rules update.

Published in Divine Power, page(s) 14.