Alysanne's Lady Lightning

This is definitely not Chidori, but you become imbued with lightning for a single strike. You can move up to your speed without triggering attacks of opportunity and make a melee spell attack against a creature within 5 ft. of you. On a hit the creature takes 50d6 lightning damage and be affected by the slow spell. At the end of an affected creature's turn, they can make a Constitution saving throw to remove this effect, it otherwise remains until they complete a long rest.