Thunderstorm Rage is a daily power available to the Barbarian class at level 29.[PrP:24]
Thunderstorm Rage
Barbarian Attack 29
Melee weapon
Target: one creature
Attack: Strength vs AC
Hit: 3[W] + Strength modifier damage, and the target takes ongoing 15 lightning damage (save ends)
Miss: half damage and the target takes ongoing 5 lightning damage (save ends).
Effect: You enter the rage of the thunderstorm. Until the rage ends, once per round when you make an attack roll against an enemy and hit, you can make the attack roll a second time against that enemy. If the second attack roll also hits, the attack deals 2[W] extra thunder damage.