Weapon of Peace Fortold
Cleric Attack 13
Melee weapon
Target: One creature
Attack: Strength vs. AC
Hit: 3[W] + Strength modifier damage. If wielding a simple weapon, the attack deals 1d6 extra damage.
Effect: The target's next attack deals half damage, and the target provokes opportunity attack whenever it makes a weapon attack. These effects last until the end of your next turn.
Weapon of Peace Foretold is a 13th level cleric encounter attack power introduced in Battle Cleric Options, a Dragon Magazine #400 article. It is designed to inhibit enemy attacks.
It is rated as a poor choice, with the reasoning that the opportunity attack effect doesn't work as written (as the effect only works on attacks with the weapon keyword, which only a subset of monsters use.)