dark energy ball

A dark energy ball glowing from your pointing finger to a point you choose within range and then enlarges with a low roar into an explosion of lightning . Each creature in a 20-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 8d6 lightning damage on a failed save, or half as much damage on a successful one.

The lightning spreads around corners. It ignites flammable objects in the area that aren't being worn or carried.

At Higher Levels. When your level increases, the damage increases by 1d6 for each  level above 4rd.