Cheapest priced copy (Tarkir: Dragonstorm Commander): $0.49 at Card Kingdom, near mint, their price list as of .
Bone Devourer 
Creature — Dragon · 2/2 · Rare · Tarkir: Dragonstorm Commander · #26
Flash
Flying
This creature enters with a number of +1/+1 counters on it equal to the number of creatures that died this turn.
When this creature dies, you draw X cards and you lose X life, where X is the number of +1/+1 counters on it.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $0.49 to $0.69 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Tarkir: Dragonstorm Commander | 26 | Rare | $0.49 | — |
| Tarkir: Dragonstorm Commander | 66 | Rare | $0.69 | — |
One ruling from Wizards of the Coast
- 4 April 2025If Bone Devourer has +1/+1 counters put on it, and then enough -1/-1 counters are put on it to cause its toughness to be 0, X is equal to the number of +1/+1 counters it had at the time those -1/-1 counters were put on it.