Ball of Black Flames

A maelstorm of swirling black fire appears near your hands. On your turn, you can choose a spot within range as an action, the maelstrom disappears from your hands and reappears centered on that point, grown exponentially. Each creature in a 20-foot-radius sphere centered on the point must make a Dexterity saving throw. A target takes 6d6 fire damage and 6d6 necrotic damage on a failed throw and takes half as much damage on a success. The maelstrom spreads around corners. It ignites flammable objects in the area that aren't being worn or carried, and it withers nonmagical, normal plants.

At Higher Levels. When you cast this spell using a spell slot of 6th level or higher, the damage increases by 2d6 for each slot level above 5th.