Cheapest priced copy (Double Masters): $0.35 at Card Kingdom, near mint, their price list as of .
Parasitic Strix 
Artifact Creature — Bird · 2/2 · Common · Salvat 2011 · #48
Flying
When this creature enters, if you control a black permanent, target player loses 2 life and you gain 2 life.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
3 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Double Masters | 60 | Common | $0.35 | $0.49 |
| Conflux | 32 | Common | $0.35 | $0.49 |
| Salvat 2011 | 48 | Common | — | — |
2 rulings from Wizards of the Coast
- 7 August 2020If you don't control a black permanent immediately after Parasitic Strix enters the battlefield, its ability doesn't trigger. If you don't control one as the ability resolves, no player loses or gains life. It doesn't have to be the same black permanent both times, however.
- 7 August 2020Parasitic Strix's ability triggers only once, no matter how many black permanents you control beyond the first.