The Ooze is a rare Legendary Artifact card from Teenage Mutant Ninja Turtles (TMT), collector number 277. Current market price: $6.82 (foil $7.97), TCGplayer market prices via Scryfall.
Whenever a creature you control with a +1/+1 counter on it leaves the battlefield, create a Mutagen token for each +1/+1 counter on it. (A Mutagen token is an artifact with "{1}, {T}, Sacrifice this token: Put a +1/+1 counter on target creature. Activate only as a sorcery.") {T}: Exile target card from a graveyard. Create a Mutagen token.