Imprint — When Chrome Mox enters the battlefield, you may exile a nonartifact, nonland card from your hand.
: Add one mana of any of the exiled card's colors to your mana pool.
6/8/2016 If no card is imprinted on Chrome Mox, it can’t add mana to your mana pool. It can never add colorless mana to your mana pool, even if the imprinted card has a colorless mana symbol in its mana cost.
6/8/2016 If you imprinted a multicolored card, you choose one of that card’s colors each time Chrome Mox’s ability resolves.