Annihilation

Summon the true annihilating power of hell fire and force. A spherical wave of black fire and force explode from the caster. Starting slow, the wave of force and flame pick up speed exponentially fast.  All creatures within a 300ft diameter, centered on the caster, must make a Dex save. A successful save takes half damage. A failed save takes full damage. Everything within the area of effect is incinerated and blown apart dealing 3d10 fire damage (fire immunity is reduced to resistance, fire resistance has no effect) and 3d10 force damage.