Ixhel, Scion of Atraxa (Phyrexia: All Will Be One Commander 1) - Mythic Magic: The Gathering Card

Flying, vigilance, toxic 2
Corrupted — At the beginning of your end step, each opponent who has three or more poison counters exiles the top card of their library face down. You may look at and 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 those spells.