You speak a word of power as you strike your foe, and the foe becomes vulnerable to your allies' attacks.

Encounter   ✦     Arcane, Weapon
Standard Action      Melee weapon

Target: One creature

Attack: Charisma vs. AC

Hit: 3[W] + Charisma modifier damage. Until the end of your next turn, each ally who hits the target and has combat advantage against it deals extra damage equal to your Charisma modifier.

Published in Player's Handbook 2, page(s) 75.