Bijuu Bomb

Bijuu Bomb is a monstrous bomb that can be created by sorcerers, wizards, and warlocks. The bijuu bomb is an 8th Level spell that is basically half the power of a nuclear warhead. It explodes in a circle with a diameter of 20ft and everyone in it has to make a Dexterity saving throw of 18. On failed save, the target takes 20d6 Fire damage and takes 5d4 of fire damage after their turn, every turn for 1d4 turns. Every spell level higher is 2d6 of damage to the overall damage. On success they take half damage and suffer 5d6 of fire damage. This can only be used every 2 long rests.