Rhythm of Disorientation
Bard Attack 23
A clatter of sounds surrounds your foes, causing them to lose their balance and creating opportunities for your allies to attack.
Area burst 2 within 10 squares
Target: Each enemy in burst
Attack: Charisma vs. Will
Hit: 1d6 + Charisma modifier thunder damage, and you knock the target prone. In addition, any ally of yours adjacent to the target can make a melee basic attack against it as a free action.
Rhythm of Disorientation is an encounter power available to bards at the 23rd level.[PH2:76]