Cheapest priced copy (Archenemy): $0.69 at Card Kingdom, near mint, their price list as of .
Kilnmouth Dragon 
Creature — Dragon · 5/5 · Rare · Legions · #104
Amplify 3 (As this creature enters, put three +1/+1 counters on it for each Dragon card you reveal in your hand.)
Flying
{T}: This creature deals damage equal to the number of +1/+1 counters on it to any target.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
4 printings · $0.69 to $54.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Archenemy | 44 | Rare | $0.69 | — |
| Duel Decks: Knights vs. Dragons | 59 | Rare | $1.29 | — |
| Legions | 104 | Rare | $2.79 | $54.99 |
| The List | DDG-59 | Rare | $1.29 | — |