Vader

Deathtouch
When Vader enters the battlefield, look at the top
four cards of target opponent's library, exile all
artifact cards or any one card. Place card(s) face
down, then put the rest on the bottom of that
library in a random order. You may look at and
cast exiled card(s) for as long as they remain
exiled, and you may spend mana as though it
were mana of any type to cast exiled spell(s).