Glassworks // Shattered Yard (DSK #137)

Glassworks — {2}{R}

Enchantment — Room

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.)

Shattered Yard — {4}{R}

Enchantment — Room

At the beginning of your end step, this Room deals 1 damage to each opponent.
(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.)

Illustrated by Sergey Glushakov