Cheapest priced copy (Commander Legends): $0.49 at Card Kingdom, near mint, their price list as of .
Necrotic Hex 
Sorcery · Rare · Commander Legends · #649
Each player sacrifices six creatures of their choice. You create six tapped 2/2 black Zombie creature tokens.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
4 printings · $0.49 to $3.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Legends | 137 | Rare | $0.49 | $0.79 |
| Commander Legends | 649 | Rare | $1.99 | $3.49 |
| Foundations Commander | 118 | Rare | $0.49 | — |
| Starter Commander Decks | 95 | Rare | $0.49 | — |
2 rulings from Wizards of the Coast
- 10 November 2020Let's say everyone controls lots of creatures. As Necrotc Hex resolves, first the player whose turn it is (likely you) chooses which six creatures they'll sacrifice, then each other player in turn order does the same, knowing the choices of players before them. Then all creatures are sacrificed simultaneously. Finally, you'll create the six tapped Zombies.
- 10 November 2020You'll create six tapped Zombies no matter how many creatures you sacrifice.