Eraser Cannon

You gather magic around you, surrounding yourself in a green aura. You condense that aura into a ball of green energy. Make a ranged spell attack against a target you can see within range. On a hit, the creature takes 10d12 force damage. When the attack comes into contact with the target or any other solid object, it explodes, dealing additional damage in a sphere with a 50ft radius. Each creature caught within range must make a Dexterity saving throw. A creature takes 20d6 force damage on a failed save and half as much damage on a successful one.