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Weapon of Final Peace
Cleric Attack 27

Melee weapon

Target: One Creature

Attack: Strength vs. AC

Hit: 2[W}+Strenght modifier damage.
Weapon: If wielding a simple weapon, the attack does 2d6 extra damage.

Effect: The first time the target attacks before the end of your next turn, it takes damage equal to that attack’s damage roll immediately after the attack. This damage ignores resistances and immunities.

Weapon of Final Peace is a 27th-level Cleric encounter attack power, introduced in Battle Cleric Options.[Dr400]

It is rated as a poor choice, although there is not much justification. The rating for character optimization has a description of it performing only half damage, which mismatches the effects of the power.[Charop cleric]. While mirroring damage does seem interesting, it is less effective if the enemy uses a low-damage attack (e.g. an opportunity attack or something similar) or a multi-target attack. The power's wording can also imply that a miss on an attack doesn't have an effect (as a miss has no damage roll.)