Cheapest priced copy (Oath of the Gatewatch): $0.35 at Card Kingdom, near mint, their price list as of .
Eldrazi Aggressor 
Creature — Eldrazi Drone · 2/3 · Common · Oath of the Gatewatch · #95
Devoid (This card has no color.)
This creature has haste as long as you control another colorless creature.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Oath of the Gatewatch | 95 | Common | $0.35 | $0.49 |
One ruling from Wizards of the Coast
- 22 January 2016If it's the turn Eldrazi Aggressor comes under your control, and it loses haste after being declared as an attacker, it will continue to attack. It won't be removed from combat.