Teth's Unstable Blast

Streaks of energies leaves your hands and shoots out at a creature. Make a ranged spell attack against the target. When you roll a 1 on two or more of the d4 dice, the spell explodes. Make a Constitution saving throw against your spell save DC. On success you take no damage and on fail you take half damage rounding up. 

The damage type is decided on the damage rolled

1-4 Damage = Cold

5-8 Damage = Lightning

9-12 Damage = Force

This spell's damage increases by 1d8 when you reach 5th level (3d4 + 1d8), 11th level (3d4 + 2d8), and 17th level (3d4 + 3d8).