Glassworks // Shattered Yard - Duskmourn: House of Horror - 137

Enchantment — Room

Mana Cost: {2}{R}

When you unlock this door, this Room deals 4 damage to target creature an opponent controls.
(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.)

Common · Duskmourn: House of Horror · #137 (DSK)

Illustrated by Sergey Glushakov