You lend your deity's guidance to an ally's attack against your foe.

Encounter   ✦     Divine
Immediate Interrupt      Close burst 10

Channel Divinity: You can use only one channel divinity power per encounter

Trigger: An ally within 10 squares of you makes an attack roll against your oath of enmity target

Target: The triggering ally

Effect: The target makes a second attack roll and uses either result.

Published in Player's Handbook 2, page(s) 34.