Charge

You build a charge while running and then release it in a devastating electric punch. After casting this spell, before the end of your next turn, you can spend a bonus action to deliver the punch, which ends the spell. The target must make a Dexterity saving throw, taking 6d8 lightning damage on failed save or half as much damage on a successful save.

The spell become more powerful if you move in a straight line toward your target immediately before delivering the punch. For every 5 feet moved this way, replace one of the damage dice with a d12. Make the substitution before rolling.