Restricted Office // Lecture Hall (DSK-227) - 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.)
When you unlock this door, destroy all creatures with power 3 or greater.

(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.)
Other permanents you control have hexproof.