Darastrix's Incinerating Fireball

You hurl a ball of flame at a point within range that becomes an enormous explosion . Each creature in a 30-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 8d8 fire damage on a failed save, or half as much damage on a successful one.  Affected targets continue to burn, taking an extra 1d8 fire damage at the start of each round until they spend an action extinguishing the flames.

The fire spreads around corners. It 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 1d8 for each slot level above 3rd.