What does Karn, Scion of Urza do?
user
[+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.\n[−1]: Put a card you own with a silver counter on it from exile into your hand.\n[−2]: Create a 0/0 colorless Construct artifact creature token with "This creature gets +1/+1 for each artifact you control."
assistant