Detonation

You call forth the power of the elements, filling your body to the brim until it quite literally explodes outward. Upon casting the spell, choose an element type (Fire, cold, shock, acid, thunder, poison). The veins in your body seem to glow with a corresponding element until you detonate. 

Each creature within 10ft in all directions of you take 10D10 damage of the element you chose. The caster immediately takes half the damage, ignoring any resistance they might have. Each creature hit by the spell must make a DEX saving throw. On a success, they take only half damage. On a failure, they take full damage.

If you cast this spell using a spell slot of 6th level or higher, increase the number of dice used in the spell by 1D10.