Storm Drake Rage is a daily power available to the Barbarian class at level 19.[PH2:58]
Storm Drake Rage
Barbarian Attack 19
Lightning cascades around you and flows into your enemy. As your rage, lightning lashes out at any foe that strikes you, knocking it to the ground.
Melee weapon
Target: one creature
Attack: Strength vs AC
Hit: 3[W] + Strength modifier damage and the target takes ongoing 10 lightning damage (save ends)
Miss: half damage.
Effect: You enter the rage of the storm drake. Until the rage ends, any enemy that hits you with a melee attack takes 5 lightning damage and is knocked prone.