Cheapest priced copy (Oath of the Gatewatch): $1.29 at Card Kingdom, near mint, their price list as of .
Inverter of Truth 
Creature — Eldrazi · 6/6 · Mythic · Oath of the Gatewatch · #72
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.
Legal inCommanderModernLegacyVintage
Banned inPioneer
Not legal inBrawlStandardPauper
2 printings · $1.29 to $9.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Oath of the Gatewatch | 72 | Mythic | $1.29 | $6.99 |
| Oath of the Gatewatch Promos | 72s | Mythic | — | $9.99 |
2 rulings from Wizards of the Coast
- 22 January 2016No player can look at the cards once they’re exiled.
- 22 January 2016If 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).