Dazzling Theater // Prop Room

(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.)
Dazzling Theater
Creature spells you cast have convoke. Your creatures can help cost those spells. Each creature you tap while casting a creature spell pays for 1 or one mana of that creature's color.)
Prop Room
Untap each creature you control during each other player's untap step.