Diamond in the Rough

When Diamond in the Rough enters the
battlefield, search your library for a Rare, Mythic
Rare, or foil card. Reveal it and put it into your
hand. Shuffle your library afterwards.
{t}: Add 1 mana of any color to your mana pool.
Spend this mana only to cast, or activate abilities
of Rare, Mythic Rare, and foil cards.