Electrocution

Lightning arcs wreathe one creature you can see within range. The target must make a Dexterity saving throw. It takes 8d6 lightning damage on a failed save, or half as much damage on a successful one. On a failed save, the target is also charged for the spell’s duration. The charged target sheds bright light in a 30-foot radius and dim light for an additional 30 feet. At the end of each of its turns, the target repeats the saving throw. It takes 4d6 lightning damage on a failed save, and the spell ends on a successful one. 

If damage from this spell kills a target, the target is turned to ash.