Greenhouse // Rickety Gazebo (DSK-181) - Duskmourn: House of Horror

(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)
Lands you control have ": Add one mana of any color."

(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)
When you unlock this door, mill four cards, then return up to two permanent cards from among them to your hand.