Cheapest priced copy (Tarkir: Dragonstorm): $0.35 at Card Kingdom, near mint, their price list as of .
Embermouth Sentinel 
Artifact Creature — Chimera · 2/1 · Common · Tarkir: Dragonstorm · #242
When this creature enters, you may search your library for a basic land card, reveal it, then shuffle and put that card on top. If you control a Dragon, put that card onto the battlefield tapped instead.
Legal inCommanderBrawlStandardPioneerModernLegacyVintagePauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Tarkir: Dragonstorm | 242 | Common | $0.35 | $0.49 |