Electrosphere

An orb of electricity forms around your hand and flies to your target. Creatures within a 10-foot-radius of the target must make a Dex saving throw. On a failed save they take 10d6 lightning damage, and on a successful save they take half as much. 

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