The rhythm of your attack makes the earth quake beneath your and your allies' targets.

Encounter   ✦     Arcane, Weapon
Standard Action      Melee weapon

Target: One creature

Attack: Charisma vs. AC

Hit: 2[W] + Charisma modifier damage, and you knock the target prone. Until the end of your next turn, each ally within 10 squares of you can knock prone any creature he or she hits.

  Virtue of Valor: Until the end of your next turn, the allies gain a bonus to damage rolls equal to your Constitution modifier.

Published in Player's Handbook 2, page(s) 73.