Atomic Strike

A blinding light flashes from a point you choose within range and explodes with a thunderous roar as a mushroom cloud rises 60 feet in the air. Each creature in a 25-foot-radius sphere centered on that point must make a Constitution saving throw. A target takes 8d8 fire damage on a failed save, or half as much damage on a successful one. Each Creature within a 75-foot-radius sphere centered on the center of the previous circle must make another Constitution saving throw. A target takes 4d8 poison damage and 4d8 necrotic damage on a failed save, or half as much on a successful one.

Each creature and object inside a ten foot radius is instantly vaporized, killing large and smaller creatures instantly, regardless of saving throws.

At Higher Levels. When you cast this spell using a spell slot of 8th level or higher, the fire damage increases by 2d8 for each slot level above 7th, and the poison and necrotic damage increases by 1d8 per level above 7th.