Karn, Scion of Urza is a mythic Legendary Planeswalker — Karn card from Dominaria Promos (PDOM), collector number 1s. Current market price: — (foil $19.31), TCGplayer market prices via Scryfall.
+1: Reveal the top two cards of your library. An opponent chooses one of them. Put that card into your hand and exile the other with a silver counter on it. −1: Put a card you own with a silver counter on it from exile into your hand. −2: Create a 0/0 colorless Construct artifact creature token with "This token gets +1/+1 for each artifact you control."