Unlocking a door

Unlocking a door
Mechanic
Type	Activated
Introduced	Duskmourn: House of Horror
Last used	Alchemy: Duskmourn
Reminder Text	As a sorcery, you may pay the mana cost of a locked door to unlock it.
Statistics	30 cards 20% 16.7% 20% 20% 13.3% 3.3% 6.7%
Scryfall Search
fulloracle:"Unlocking a door"

Not to be confused with Unlock counter.

Unlock a door is a special action used on Room cards, introduced in Duskmourn: House of Horror. Unlocking a door changes its state from locked to unlocked.

Description

A bi-colored Room card, horizontally aligned

When a room enters the battlefield, its doors (halves) are initially locked. If it was cast, the door of the half that was cast immediately becomes unlocked when it enters the battlefield. As a sorcery, the mana cost of a locked door can be paid to unlock it. Unlocking a door this way is a special action: it doesn't use the stack and can't be responded to.

Rules

Duskmourn punch card for "Locked" Doors.

From the Comprehensive Rules (September 20, 2024—Duskmourn: House of Horror)

• 116.2m A player who controls a permanent that has one or more locked halves (see rule 709.5) may pay the mana cost of a locked half of that permanent to give that permanent the appropriate unlocked designation. This cost is referred to as an “unlock cost.” A player can take this action any time they have priority and the stack is empty during a main phase of their turn.

From the glossary of the Comprehensive Rules (September 20, 2024—Duskmourn: House of Horror)

Door

A door is one half of a Room permanent. See rule 709, “Split Cards.”

From the glossary of the Comprehensive Rules (September 20, 2024—Duskmourn: House of Horror)

Room

1. A subsection of a dungeon card. See rule 309, “Dungeons.”

2. An enchantment subtype found on some split cards. See rule 709, “Split Cards.”

From the glossary of the Comprehensive Rules (September 20, 2024—Duskmourn: House of Horror)

Lock

To remove an unlocked designation from a permanent that has one or more unlocked halves. See rule 709.5g.

From the glossary of the Comprehensive Rules (September 20, 2024—Duskmourn: House of Horror)

Unlock

To give an unlocked designation to a permanent that has one or more locked halves. See rule 709.5f.

From the glossary of the Comprehensive Rules (September 20, 2024—Duskmourn: House of Horror)

Locked

One half of a split permanent is “locked” if it doesn’t have the appropriate unlocked designation. See rule 709.5.

From the glossary of the Comprehensive Rules (September 20, 2024—Duskmourn: House of Horror)

Unlocked

One half of a split permanent is “unlocked” if it has the appropriate unlocked designation. See rule 709.5.

Rulings

• Any time you have priority during a main phase of your turn and the stack is empty, you may pay the mana cost of a locked door (also called its "unlock cost"). That door becomes unlocked. This is a special action. It doesn't use the stack and can't be responded to.
• An ability that triggers "when you unlock this door" triggers when that door becomes unlocked. This can happen one of two ways: (1) the door becomes unlocked on the battlefield or (2) the door becomes unlocked as the Room enters the battlefield because you cast the corresponding half. In the latter case, since the door becoming unlocked is what causes the ability to trigger, effects that cause abilities that trigger when a permanent enters to trigger an additional time (such as that of Panharmonicon) won't apply.
• Some abilities allow you to unlock a door of a Room you control. You can't choose to unlock a door that's already unlocked with such an ability. If such an ability requires a target, you can target a Room even if both of its doors are unlocked, but the ability won't do anything when it resolves.
• Some abilities allow you to lock a door of a Room you control. You can't choose to lock a door that's already locked with such an ability. If such an ability requires a target, you can target a Room even if both of its doors are locked, but the ability won't do anything when it resolves.
• Some doors have abilities that trigger whenever you unlock that door and require one or more targets. You can unlock that door even if there would be insufficient legal targets for that triggered ability. The triggered ability won't go on the stack.
• An ability that triggers "whenever you fully unlock a Room" triggers when a door becomes unlocked and the other door of that Room is already unlocked, or when both doors of that Room become unlocked simultaneously.

Example

Duskmourn Commander punch-outs for Locked Doors.

Example

Bottomless Pool
When you unlock this door, return up to one target creature to its owner's hand.
//
Locker Room
Whenever one or more creatures you control deal combat damage to a player, draw a card.
//
Enchantment — 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.)