Jace, Wielder of Mysteries is a rare Legendary Planeswalker — Jace card from War of the Spark Promos (PWAR), collector number 54p. Current market price: $11.47 (foil $10.67), TCGplayer market prices via Scryfall.
If you would draw a card while your library has no cards in it, you win the game instead. +1: Target player mills two cards. Draw a card. −8: Draw seven cards. Then if your library has no cards in it, you win the game.