You answer an attacker's hit against an ally with a vicious riposte.

Encounter   ✦     Martial, Weapon
Immediate Reaction      Melee weapon

Trigger: An enemy within 3 squares of you hits your ally

Effect: Before your attack, you shift 2 squares.

Target: The triggering enemy

Attack: Strength vs. AC

Hit: 2[W] + Strength modifier damage.

Published in Martial Power 2, page(s) 88.