Valin's Compressed Storm Cloud

A miniature storm cloud contained within a transparent sphere of compressed air appears centered on a point you can see within range. Bolts of lightning arc from the sphere to each creature in a 15-foot-radius sphere centered on the sphere must make a Dexterity saving throw. A creature takes 8d6 lightning damage on a failed save, or half as much damage on a successful one.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d6 for each slot level above 3rd.