Cheapest priced copy (Tarkir: Dragonstorm): $0.35 at Card Kingdom, near mint, their price list as of .
Armament Dragon 
Creature — Dragon · 3/4 · Uncommon · Tarkir: Dragonstorm · #168
Flying
When this creature enters, distribute three +1/+1 counters among one, two, or three target creatures you control.
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Tarkir: Dragonstorm | 168 | Uncommon | $0.35 | $0.49 |
| Tarkir: Dragonstorm | 307 | Uncommon | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 4 April 2025If some of the creatures are illegal targets as Armament Dragon’s triggered ability resolves, the original distribution of counters still applies and the counters that would have been put on the illegal targets are lost.
- 4 April 2025You choose how many targets Armament Dragon’s triggered ability has and how the counters are distributed as you put the ability onto the stack. Each target must receive at least one counter.