Mishra's Factory is a rare Land card from Antiquities (ATQ), collector number 80b. Current market price: $200.54, TCGplayer market prices via Scryfall.
{T}: Add {C}. {1}: This land becomes a 2/2 Assembly-Worker artifact creature until end of turn. It's still a land. {T}: Target Assembly-Worker creature gets +1/+1 until end of turn.