Asgier's Voltaic blade

When this spell is cast, your blade is enshrouded in an electrical coat that discharges high voltage electricity. When using this spell, all melee attack rolls against another creature deal an extra 1d8 of lightning damage, and any creature hit while the spell is active must make a constitution saving throw. On a failed save the creature has the stunned condition until the end of its next turn, on a successful save the creature is not stunned.

At higher levels: When casting this spell using a spell slot higher than 1st, the damage of the spell increases by 1d8.