Vengeful Ghosts is a 9th level cleric Daily power that was introduced in Heroes of Shadow.
Vengeful Ghosts
Cleric Attack 9
With a shout, you draw forth a howling horde of restless spirits to wreak havoc on your foes.
Close blast 3
Target: Each enemy in the blast
Attack: Wisdom vs. Will
Hit: 2d8 + Wisdom modifier necrotic damage.
Miss: Half damage.
Effect: The blast creates a zone that lasts until the end of the encounter. Enemies grant combat advantage while in the zone.