Unexplored Lands

If you choose to play Unexplored Lands in your
deck, purchase a pack of your choice, and open it.
Begin each game with Unexplored Lands in your command zone, and the cards from that pack
exiled face down.
You may play cards exiled with Unexplored
Lands, you may spend mana as though it were
mana of any type to cast spells this way.
If a card exiled with Unexplored Lands would be
put anywhere other than the battlefield, exile it instead.