Cheapest priced copy (Modern Horizons 3 Commander): $0.99 at Card Kingdom, near mint, their price list as of .
Kozilek's Return 
Instant · Mythic · Oath of the Gatewatch · #98
Devoid (This card has no color.)
Kozilek's Return deals 2 damage to each creature.
Whenever you cast an Eldrazi creature spell with mana value 7 or greater, you may exile this card from your graveyard. If you do, this card deals 5 damage to each creature.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
3 printings · $0.99 to $8.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Modern Horizons 3 Commander | 214 | Mythic | $0.99 | $4.99 |
| Oath of the Gatewatch | 98 | Mythic | $0.99 | $7.99 |
| Oath of the Gatewatch Promos | 98s | Mythic | — | $8.99 |
2 rulings from Wizards of the Coast
- 22 January 2016Exiling Kozilek's Return due to the last ability isn't the same as casting it as a spell. Cards that say "Counter target spell" won't work.
- 22 January 2016The last ability triggers only if Kozilek's Return is in your graveyard as you cast the Eldrazi creature spell. That ability will resolve before the Eldrazi creature spell does. In other words, that Eldrazi won't be on the battlefield yet and won't be dealt damage by Kozilek's Return.