Ghost Viper Rage is a daily power available to the Barbarian class at level 19.[PH2:58]
Ghost Viper Rage
Barbarian Attack 19
The spirit of the ghost viper infuses you, sending venom coursing through the veins of your foe. As you rage, the viper's spirit throws nearby foes off guard.
Melee weapon
Target: one creature
Attack: Strength vs AC
Hit: 3[W] + Strength modifier damage and the target takes ongoing 10 poison damage (save ends).
Miss: half damage.
Effect: You enter the rage of the ghost viper. Until the rage ends, any enemy that starts its turn next to you grants combat advantage to you and your allies until the end of its next turn.