Cheapest priced copy (Aetherdrift Commander): $0.49 at Card Kingdom, near mint, their price list as of .
Dread Summons 
Sorcery · Rare · Aetherdrift Commander · #90
Each player mills X cards. For each creature card put into a graveyard this way, you create a tapped 2/2 black Zombie creature token. (To mill a card, a player puts the top card of their library into their graveyard.)
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
6 printings · $0.49 to $1.29 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2015 | 20 | Rare | $0.79 | — |
| Commander Anthology | 56 | Rare | $1.29 | — |
| Aetherdrift Commander | 90 | Rare | $0.49 | — |
| Foundations | 604 | Rare | $0.49 | — |
| Midnight Hunt Commander | 113 | Rare | $0.69 | — |
| New Capenna Commander | 249 | Rare | $0.69 | — |
One ruling from Wizards of the Coast
- 4 November 2015If a creature card has an ability that replaces going to the graveyard with moving somewhere else "instead," that card won't count toward the number of Zombies you get. Conversely, creature cards with a triggered ability that removes them from the graveyard when they're put there from anywhere (or your library) will count toward that number.