As lightning strikes your foe, thunder batters creatures around it.

Encounter   ✦     Arcane, Implement, Lightning, Thunder
Standard Action      Ranged 10

Target: One creature

Attack: Charisma vs. Reflex

Hit: 2d10 + Charisma modifier lightning damage, and each creature adjacent to the target takes thunder damage equal to your Charisma modifier.

Published in Player's Handbook 2, page(s) 140.