Blood-Spattered Frenzy is an encounter power available to the Barbarian class at level 17.[PrP:18]
Blood-Spattered Frenzy
Barbarian Attack 17
You whirl around, bathing your enemies in their own blood.
Close burst 1
Requirement: You must be wielding two melee weapons
Target: Each creature in burst.
Attack: Strength vs AC
Whirling Slayer: The attack can target Reflex instead of AC.
Hit: 2[W] + 1[W] (off-hand weapon) + Strength modifier damage.