Alarza, Warper of Realms

Target player must play with the top card of
their library revealed. You may put the top card
of their library on the bottom of the deck.
Pay {u}{u}{g}{g}: Exile the top card of target
player's library.
Pay {u}{u}{g}{g}: You may cast a card exiled
with Alarza, Warper of Realms and you may
use any mana to cast that card.