Invoker Utility 22Covenant of Vengeance
You forge a covenant with your ally. Anyone foolish enough to attack that ally will suffer your wrath.
Minor Action Close burst 10
Target: You or one ally in the burst
Effect: All of the target’s marks end. Until the end of the encounter or until the target marks a creature, if a creature attacks the target, you and your allies gain a +4 power bonus to attack rolls against that creature until the end of your next turn.
Published in Player's Handbook 2, page(s) 111.