Rage of the Primal Beast is a daily power available to the Barbarian class at level 29.[PH2:61]
Rage of the Primal Beast
Barbarian Attack 29
Melee weapon
Target: one creature
Attack: Strength vs AC
Hit: 5[W] + Strength modifier damage, and the target takes ongoing 10 damage (save ends).
Miss: half damage.
Effect: You enter the rage of the Primal Beast. Until the rage ends, you gain a bonus to attack rolls equal to the number of enemies you can see.