Gunk Slug is a rare Creature — Slug card from Mystery Booster Playtest Cards 2019 (CMB1), collector number 43. Current market price: $0.40, TCGplayer market prices via Scryfall.
When Gunk Slug enters, create three Gunk token cards and shuffle them into target opponent's library. (Gunk is a colorless sorcery card with no mana cost that has cycling {4}.)