Vyss, the Truth Hunter

Flash, Hexproof, Vigilance, Deathtouch
Whenever Vyss, the Truth Hunter deals combat
damage to a player, exile the top four cards of
that player's library face down. You may look at
and play the exiled cards for as long as it remains exiled, and you may spend mana as though it
were mana of any color to cast that spells.
{4}, {t}: Target creature phases out.