Chrome Mox is a mythic Artifact card from Secret Lair Countdown (SLC), collector number 2003. Current market price: $178.69 (foil $355.47), TCGplayer market prices via Scryfall.
Imprint — When this artifact enters, you may exile a nonartifact, nonland card from your hand. {T}: Add one mana of any of the exiled card's colors.