Sunken Palace [Modern Horizons 3 Commander]

Set: Modern Horizons 3 Commander Type: Land — Cave Rarity: Rare Sunken Palace enters the battlefield tapped.T: Add U1U, T, Exile seven cards from your graveyard: Add U. When you spend this mana to cast a spell or activate an ability, copy that spell or ability. You may choose new targets for the copy. (Mana abilities can't be copied.)