Banana Bomb

On touch. You turn a banana into a bomb, that can be exploded up until 150 ft radius from the bomb at any time. Each creature in a 20-foot-radius Sphere centered on the banana makes a Dexterity saving throw, taking 8d4 Potassium damage on a failed save or half as much damage on a successful one. if it fails the first saving throw it also has to make an constitution saving throw nothing happens on a success and the target becomes irradiated on a fail taking 1d4 poison damage every turn until death or healing. the irradiated effect cant stack.

Using a Higher-Level Spell Slot. The damage increases by 1d4 for each spell slot level above 4.