Nyth, Founder of the Forgotten

Deathtouch
Nyth, Founder of the Forgotten enters the battlefield, look at the top four cards of target opponent's library, exile one of them face down,
then put the rest on the bottom of that library in
a random order. You may look at and play that
card for as long as it remains exiled, and
you may spend mana as though it were mana of
any type.