Nantuko Monastery is a uncommon Land card from Archenemy (ARC), collector number 131. Current market price: $0.20, TCGplayer market prices via Scryfall.
{T}: Add {C}. Threshold — {G}{W}: This land becomes a 4/4 green and white Insect Monk creature with first strike until end of turn. It's still a land. Activate only if there are seven or more cards in your graveyard.