You magically split an atom, creating an explosion with radioactive fallout. All targets in the area take 5d12 bludgeoning damage and 5d12 fire damage, and they're exposed to extreme radiation that uses your spellcasting DC as the Fortitude DC for radiation sickness incurred by exposure to this radiation. The onset and frequency of this magical radiation is 1 round, and the area remains radioactive for 10 minutes.
Critical Success The target is unaffected by the initial damage.
Success The target takes half damage and is dazzled for 1 minute.
Failure The target takes full damage and is blinded for 1 minute.
Critical Failure As failure, and the target takes double damage.