Cheapest priced copy (March of the Machine): $0.35 at Card Kingdom, near mint, their price list as of .
Halo-Charged Skaab 
Creature — Zombie · 4/4 · Common · March of the Machine · #60
When this creature enters, each player mills two cards. Then you may put an instant, sorcery, or battle card from your graveyard on top of your library. (To mill two cards, a player puts the top two cards of their library into their graveyard.)
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| March of the Machine | 60 | Common | $0.35 | $0.49 |
One ruling from Wizards of the Coast
- 14 April 2023The card you put on top of your library, if any, may be one you just milled, or it can be one that was already in your graveyard.