Otogakure

Hideaway (This land enters the battlefield
tapped. When it does, look at the top four cards
of your library, exile one face down, then put
the rest on the bottom of your library.)
{t}: Add {c} to your mana pool.
{x}, {t}: You may play the exiled card without
paying it's mana cost if X is equal to it's
converted mana cost.