Mera of the Secret Garden

Hideway (Whenever this creature enters the battlefield, look at the top four cards of your library, exile one face down, then put the rest on the bottom of your library. You may look at those cards as long as they remain exiled face-down.)
During each of your turns, you may cast a card exiled by Mera of the Secret Garden by paying only the colored mana in its mana cost required to cast it. If you do, exile Mera, then return her to the battlefield under her owner's control.