Shelldock Isle

Hideaway 4(When this land enters the
battlefield, look at the top four cards of your
library, exile one face down, then put the rest on the
bottom in a random order.)
Shelldock Isle enters the battlefield tapped.
{t}: Add {u}.
{u}, {t}: You may play the exiled card without paying its mana cost if a library has twenty or fewer cards in it.