Living Brain, Mechanical Marvel is a uncommon Legendary Artifact Creature — Robot Villain card from Marvel's Spider-Man (SPM), collector number 167. Current market price: $0.12 (foil $0.19), TCGplayer market prices via Scryfall.
At the beginning of combat on your turn, target non-Equipment artifact you control becomes an artifact creature with base power and toughness 3/3 until end of turn. Untap it.