Ninja Trianing Grounds

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 {1} to your mana pool.
{t}: Add {2} your mana pool to cast Ninja spells.
{u}{r},{t}: You may play the exiled card without paying its mana cost if you control Four or more ninjas.