Clarion Call p. 91
As you defeat an opponent, you shout a battle cry that inspires one of your allies to renew his efforts.
You are an inspiring figure on the battlefield. Your personal victories are shared by your allies, allowing them to draw courage and vigor from your actions. If during your turn a melee attack you make reduces an opponent to fewer than 0 hit points, you can initiate this maneuver. Once it is initiated, all allies within range can immediately either make one melee attack at their highest attack bonus or take a single move action. These allies must be able to see and hear you. These extra attacks are not attacks of opportunity.