Cheapest priced copy (Oath of the Gatewatch): $0.35 at Card Kingdom, near mint, their price list as of .
Umara Entangler 
Creature — Merfolk Rogue Ally · 2/1 · Common · Oath of the Gatewatch · #65
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
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 | 65 | Common | $0.35 | $0.49 |