Storm of Vengeance

The acid damage dealt increases to 1d8 points of acid damage. The lightning damage dealt increases to 10d8 points of electricity damage. You can call down a bolt of lightning on the 2nd and 4th rounds (equivalent to those on the 3rd round). You can strike the same target with a bolt more than once during the casting of the spell, but not more than once per round.

Augmented (7th): If you expend three uses of mythic power, the storm cloud's radius increases to 1,000 feet. Structures in the storm take 1d10 points of damage per round (this damage bypasses hardness). You can call down one additional bolt in the 2nd and 4th rounds, and three additional bolts in the 3rd round.