Voltraghoth

A thunderous storm explodes in a 10-foot radius at a point you choose within range. Creatures in the area must make a Dexterity saving throw. On a failed save, they take 7d6 lightning damage. Targets wearing metal armor automatically fail the save. On a success, they take half damage.

At Higher Levels:
When cast using a spell slot of 5th level or higher, the damage increases by 1d6 per slot level above 4th.