Sableye

When Sableye enters the battlefield, look at the
top two cards of target opponent's library. Exile
one of them face down and put the other on the
bottom of that library. You may look at and
play the exiled card for as long as it remains
exiled, and you may spend mana as though it
were mana of any color to cast that spell.
"It feeds on gemstone crystals. In darkness, its eyes
sparkle with the glitter of jewels." - Pokedex