You, Magic Playtester is a mythic Legendary Creature — Human Gamer card from Unknown Event (UNK), collector number MW02. Current market price: $25.50, TCGplayer market prices via Scryfall.
{T}: Choose target playtest card. Increase or decrease a number of your choice on it by one for as long as it remains on the stack or battlefield. {W}{U}{B}{R}{G}: Reveal the top 8 cards of your library. Put each playtest card among them into your hand, and the rest on the bottom of your library in a random order.