Arcane Diffusion Bomb

When you cast this spell, you choose an area within 60 feet of your current position. You then spend one hour welling up arcane energy into a single focused point. It then launches from your location and then after 1d4 rounds it lands. When it lands several things happen. First, all creatures with 30 feet take 20d8 + 150 magic bludgeoning damage. Creatures within 120 feet of the horrible explosion have to make a Fortitude save or take 20d8 +50 radiant damage; half damage on a success. All non-magical plant life within 300 feet withers and dies. The 30 foot radius around the detonation point becomes a dead magic zone having been torn apart by this horrible thing you’ve created. For the next 1d10 days, any creature that enters this dead magic zone takes 15 radiant damage every round. This is, essentially, a nuclear warhead for wizards and sorcerers.