Cheapest priced copy (Oath of the Gatewatch): $0.35 at Card Kingdom, near mint, their price list as of .
Spawnbinder Mage 
Creature — Human Wizard Ally · 2/4 · Common · Oath of the Gatewatch · #35
Cohort — {T}, Tap an untapped Ally you control: Tap target 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 | 35 | Common | $0.35 | $0.49 |
One ruling from Wizards of the Coast
- 22 January 2016To activate a cohort ability, the Ally with that ability must have been under your control continuously since the beginning of your most recent turn. Informally, it can’t have “summoning sickness.” However, the other Ally you tap can be one that just came under your control. (Note that tapping the second Ally doesn’t use {T} [the tap symbol].)