Carrion Grub is a uncommon Creature — Insect card from Duskmourn: House of Horror Commander (DSC), collector number 134. Current market price: $0.19, TCGplayer market prices via Scryfall.
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.)