Electrosphere

A narrow lighting bolt flashes from your pointing finger to a point you choose within range and then erupts into a sphere of crackling lighting, which lasts for a duration of 400ms. Each creature in a 10-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 8d6 lighting damage on a failed save, or half as much damage on a successful one.

The lighting ignites flammable objects in the area that aren't being worn or carried.

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.