If the target creature is an illegal target by the time Stolen by the Fae tries to resolve, the spell won't resolve. You won't create any Faerie tokens.
04-10-2019
wotc
If a creature on the battlefield has {X} in its mana cost, X is considered to be 0.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.