Frenzied Beast Rage is a daily power available to the Barbarian class at level 9.[PHH2:PH2]
Frenzied Beast Rage
Barbarian Attack 9
You are so consumed with primal fury that you enter a self-destructive rampage.
Melee weapon
Target: One creature
Attack: Strength vs. AC
Hit: 3[W] + Strength modifier damage.
Miss: Half damage.
Effect: You enter the rage of the frenzied beast. Until the rage ends, once per round as a minor action you can take 5 damage to deal 5 + your Constitution modifier damage to an enemy adjacent to you. The damage you take cannot be reduced or negated.