Hidden Nursery (Ripple Foil) [Modern Horizons 3 Commander]

Hidden Nursery enters the battlefield tapped.
T: Add G.
4G, T, Sacrifice Hidden Nursery: Discover 4. Activate only as a sorcery. (Exile cards from the top of your library until you exile a nonland card with mana value 4 or less. Cast it without paying its mana cost or put it into your hand. Put the rest on the bottom in a random order.)