Ivory Rampart is a 15th level cleric Daily prayer that was introduced in Divine Power.
Ivory Rampart
Cleric Attack 15
As your weapon strikes your foe, divine power flows from you to form a barrier that protects your allies.
Daily ✦ conjuration, divine, weapon
Melee weapon
Target: One creature
Attack: Strength vs. AC
Hit: 2[W] + Strength modifier damage.
Miss: Half damage.
Effect: You conjure a wall of gleaming energy that originates in your space and can be up to 8 squares long and up to 2 squares high. The wall lasts until the end of your next turn. Any ally within the wall or adjacent to it gains cover. Any enemy that enters the wall is immobilized until the end of its turn.
Sustain minor: The wall persists.