Cheapest priced copy (Midnight Hunt Commander): $1.29 at Card Kingdom, near mint, their price list as of .
Dark Salvation 
Sorcery · Rare · Eldritch Moon · #87
Target player creates X 2/2 black Zombie creature tokens, then up to one target creature gets -1/-1 until end of turn for each Zombie that player controls.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
3 printings · $1.29 to $4.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Eldritch Moon | 87 | Rare | $1.49 | $4.49 |
| Midnight Hunt Commander | 110 | Rare | $1.29 | — |
| Eldritch Moon Promos | 87s | Rare | — | $4.99 |
3 rulings from Wizards of the Coast
- 13 July 2016You may cast Dark Salvation with X as 0 just to have a creature get -1/-1 for each Zombie a player controls, and you may cast it without targeting any creature just to have a player get Zombie tokens. If you really just want to cast a spell, you can even cast it with X as 0 without a target creature and have neither effect do anything.
- 13 July 2016You choose up to one target creature total, not a separate target for each Zombie that player controls.
- 13 July 2016If the targeted creature becomes an illegal target, the targeted player will still get Zombie tokens.