Chaos Explosion

You hurl a large, warbling mass of chaos at a point withing range. Each creature in a 20-foot-radius sphere centered on that point must make a saving throw correspondent with the damage type. A target takes 2d8+6d6 damage on a failed save, or half as much damage on a successful one.
After you roll the damage, choose one of the d8s. The number rolled determines the damage type and save.

If you roll the same number on both d8s, the area of effect is increased by 5 ft.

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.