Pact of Intrigue

Pact of Intrigue is blue and black.
Look at the top 4 cards of target opponent's
library. Exile one of them face down and put the
rest on the bottom of that player's library in any
order. As long as that card remains exiled, you
may look at it, you may cast it, and you
may spend mana as though it were mana of any
type to cast it.
At the beginning of your next upkeep, pay {3}{u}{b}. If you don't, you lose the game.