Voltage Burst

Any time you hit a creature with a melee weapon attack during this spell’s duration, the attack deals an extra 4d6 lightning damage to the target. The target must make a Wisdom saving throw. On a failed save, it has disadvantage on attack rolls and ability checks, and can’t take reactions, until the end of its next turn.

Casting at 5th level or higher allows you to deal an additonal 1d6 per level above 4th.