Conspiracy is a rare Enchantment card from Mercadian Masques (MMQ), collector number 127. Current market price: $3.12 (foil $30.00), TCGplayer market prices via Scryfall.
As this enchantment enters, choose a creature type. Creatures you control are the chosen type. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.