This card's ATK/DEF become its Level x 200. Once per turn, during your Standby Phase: Increase this card's Level by 1 (max. 12). You can target 1 "Fortune Lady" monster you control; banish any number of other Spellcaster monsters from your hand, field, and/or GY, and if you do, increase or reduce that monster's Level by the number of monsters banished, until the end of this turn. You can only use this effect of "Fortune Lady Past" once per turn.
You can banish multiple Fortune Lady monsters with Fortune Lady Past’s effect then bring them back with Fortune Lady Rewind. With the monsters on your field you can easily make Synchro plays.
Here are the monsters you can boost with Fortune Lady Past’s effect. Fortune Lady monsters’ stats depend on their level so a huge level boost could make them powerful beaters. Additionally when aiming to Synchro Summon the level manipulation can be helpful.