As two actions, a churning storm cloud forms, centered on a point you can see within sight range and spreading to a radius of 100 meters. Lightning flashes in the area, thunder booms, and strong winds roar. Each creature under the cloud (no more than 1 kilometer beneath the cloud) when it appears must make a Fortitude saving throw.
On a failure, it takes 7d6 concussion damage and is deafened 5 minutes.
On a critical failure, it takes twice as much damage.
On a success, it takes half as much damage.
On a critical success, it takes no damage.
Each round you maintain concentration on this spell, as an action, you can call six bolts of lightning from the cloud to strike six creatures or objects of your choice beneath the cloud. A given creature or object can’t be struck by more than one bolt. A struck creature must make a Reflex saving throw. The creature takes 8d6 lightning damage on a failed save, or half as much damage on a successful one.