Inverter of Truth

Devoid (This card has no color.)
Flying
When this creature enters, exile all cards from your library face down, then shuffle all cards from your graveyard into your library.

Oath of the Gatewatch

Devoid (This card has no color.)
Flying
When Inverter of Truth enters the battlefield, exile all cards from your library face down, then shuffle all cards from your graveyard into your library.

Oath of the Gatewatch Promos

If your opponent puts one of the face-down exiled cards into your graveyard (for example, to activate an ability of an Eldrazi Processor), choose one of the cards at random. The card is revealed only after the cost is fully paid. That is, your opponent can’t learn what card was chosen and decide to back up (not cast the spell, activate the ability, or so on, as applicable).

No player can look at the cards once they’re exiled.