Karn, the Great Creator

Legendary Planeswalker — Karn {4}

Activated abilities of artifacts your opponents control can't be activated. [+1]: Until your next turn, up to one target noncreature artifact becomes an artifact creature with power and toughness each equal to its mana value. [−2]: You may reveal an artifact card you own from outside the game or choose a face-up artifact card you own in exile. Put that card into your hand.