Cheapest priced copy (Outlaws of Thunder Junction): $0.35 at Card Kingdom, near mint, their price list as of .
Skulduggery 
Instant · Common · Outlaws of Thunder Junction · #107
Until end of turn, target creature you control gets +1/+1 and target creature an opponent controls gets -1/-1.
Legal inCommanderBrawlStandardPioneerModernLegacyVintagePauper
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Outlaws of Thunder Junction | 107 | Common | $0.35 | $0.49 |
| Ixalan | 123 | Common | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 29 September 2017You can't cast Skulduggery unless you choose both a creature you control and a creature you don't control as targets.
- 29 September 2017If either target becomes illegal after you cast Skulduggery but before it resolves, the other is still affected as appropriate.