Cheapest priced copy (Innistrad: Double Feature): $0.35 at Card Kingdom, near mint, their price list as of .
Skulking Killer 
Creature — Vampire Assassin · 4/2 · Uncommon · Innistrad: Crimson Vow · #130
When this creature enters, target creature an opponent controls gets -2/-2 until end of turn if that opponent controls no other creatures.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
3 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Innistrad: Double Feature | 397 | Uncommon | $0.35 | $0.49 |
| Innistrad: Crimson Vow | 130 | Uncommon | $0.35 | $0.49 |
| Innistrad: Crimson Vow | 296 | Uncommon | $0.35 | $0.49 |
One ruling from Wizards of the Coast
- 19 November 2021Skulking Killer's ability triggers even if all your opponents control more than one creature. If the targeted creature's controller controls any other creatures as the ability resolves, the ability won't do anything. Notably, that player could cast a creature spell with flash or create a creature token in response to avoid the -2/-2 effect.