Cheapest priced copy (Innistrad: Double Feature): $0.35 at Card Kingdom, near mint, their price list as of .
Serpentine Ambush 
Instant · Common · Innistrad: Double Feature · #344
Until end of turn, target creature becomes a blue Serpent with base power and toughness 5/5.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
4 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Innistrad: Double Feature | 344 | Common | $0.35 | $0.49 |
| Foundations Jumpstart | 352 | Common | $0.35 | — |
| The List | VOW-77 | Common | $0.35 | — |
| Innistrad: Crimson Vow | 77 | Common | $0.35 | $0.49 |