Gonti, Lord of Luxury

Deathtouch
When Gonti, Lord of Luxury 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 cast that card
for as long as it remains exiled, and you may spend
mana as though it were mana of any type
to cast that spell.