Cheapest priced copy (Streets of New Capenna): $0.35 at Card Kingdom, near mint, their price list as of .
Knockout Blow 
Instant · Uncommon · Streets of New Capenna · #20
This spell costs {2} less to cast if it targets a red creature.
Knockout Blow deals 4 damage to target attacking or blocking creature and you gain 2 life.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Streets of New Capenna | 20 | Uncommon | $0.35 | $0.49 |