Cheapest priced copy (Commander Masters): $0.35 at Card Kingdom, near mint, their price list as of .
Carrion Grub 
Creature — Insect · 0/5 · Uncommon · Duskmourn: House of Horror Commander · #134
This creature gets +X/+0, where X is the greatest power among creature cards in your graveyard.
When this creature enters, mill four cards. (Put the top four cards of your library into your graveyard.)
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
3 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Masters | 143 | Common | $0.35 | $0.49 |
| Duskmourn: House of Horror Commander | 134 | Uncommon | $0.35 | — |
| Core Set 2021 | 92 | Uncommon | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 23 June 2020Carrion Grub's first ability applies only while it is on the battlefield. In all other zones, its power is 0.
- 23 June 2020Any counters on creatures that die or effects that affect them until end of turn won't apply to those cards in their owner's graveyard.