Realm of Battle is a 19th level cleric Daily prayer that was introduced in Divine Power.
Realm of Battle
Cleric Attack 19
You sweep your weapon through the air and call out for divine aid. A flock of angels soars through the sky to surround you, driving back the enemy.
Melee
Target: One creature
Attack: Strength vs. AC
Hit: 3[W] + Strength modifier radiant damage.
Miss: Half damage.
Effect: The attack creates a zone of angelic soldiers in a close burst 3. The zone lasts until the end of the encounter. While within the zone, you and your allies gain a +1 power bonus to AC and attack rolls. While within the zone, any enemy takes 5 radiant damage at the start of its turn and provokes opportunity attacks when it shifts.