Earth

Earth enters the battlefield tapped. You cannot untap Earth except for in the untap stage.
{t}: add {x} mana of any type
{t},{2}: Play the top card of your deck for free, or exile it. If the card damages any creature or Planeswalker when it is played, pay the mana cost of the card + {10}. If you cannot afford it, exile your hand.
{t},{10}, Exile Earth: Play any amount of cards, ignoring mana cost, until the start of your next turn. All cards in your deck cost {u}{g} less for the rest of the game.