Cheapest priced copy (Gatecrash): $0.35 at Card Kingdom, near mint, their price list as of .
Executioner's Swing 
Instant · Common · Gatecrash · #161
Target creature that dealt damage this turn gets -5/-5 until end of turn.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Gatecrash | 161 | Common | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 24 January 2013It doesn’t matter what the creature dealt damage to or if that damage was combat damage.
- 24 January 2013You can’t choose a creature that hasn’t yet dealt damage during the turn as the target of Executioner’s Swing, so in most cases it’s not possible for Executioner’s Swing to reduce the amount of combat damage a creature deals. (If a creature has double strike, you could cast Executioner’s Swing after it deals first-strike damage but before it deals regular combat damage.)