Cheapest priced copy (Modern Horizons 2): $0.35 at Card Kingdom, near mint, their price list as of .
Breathless Knight 
Creature — Spirit Knight · 2/2 · Common · Modern Horizons 2 · #187
Flying, lifelink
Whenever this creature or another creature you control enters, if that creature entered from a graveyard or you cast it from a graveyard, put a +1/+1 counter on this creature.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Modern Horizons 2 | 187 | Common | $0.35 | $0.49 |