Opposition Assassin

Flash, Deathtouch
You control your opponents while they're
searching their libraries.
While an opponent is searching their library,
they exile each card they find. You may play
those cards for as long as they remain exiled,
and you may spend mana as though it were
mana of any color to cast them.
When Opposition Assassin deals combat damage
to a player, you may have that player search their library for card.