Can room costs be reduced

[ʍolɟ ǝɥʇ ǝsɹǝʌǝɹ]

It says as a sorcery so mindsplice aparautus?

[M3rett0]

no

[Tom the Mime Artist]

As a sorcery is a timing restriction - only during your main phase when the stack is empty and you have priority. Unlocking a door of a room on the battlefield isn't casting a sorcery, it's a special game action like flipping a cloaked creature face up. Much like flipping a creature face up, it doesn't use the stack and can't be countered (although any triggered abilities from being unlocked can be countered but only with an effect like stifle).

There are ways to cheat the cost though, with cards like ghostly keybearer.

[anaris]

you'd need something that works for rooms specifically, it's what we call a Special Action, it's not an ability or a spell or anything else, it's unlocking a room.

[ʍolɟ ǝɥʇ ǝsɹǝʌǝɹ]

I found 2 ways so far.

A WU fox glimmer [[Inquisitive Glimmer]] reduces costs or enchantments and rooms by one.
A 1 cost colorless artifact that can open a room for 3 [[keys to the house]]

[Traumaturgy]

Marina Vendrell - she can lock/unlock your rooms. But she is all 5 colors to play.
Smoky lounge- adds 2 red mana to play rooms or pay for unlocking rooms.
Ghostly keybearer- unlocks for free when dealing dmg to player
Ghostly dancers- can unlock room when entering

In paper version there is commander Aminatou who can use ability to pay 4 less mana when playing enchantments, but she is not available in Arena. The same was with Bloomburrow commanders. Its pretty stupid tbh.

[ice]

blue sorcery reduction
when that don't work farm treasure

[ʍolɟ ǝɥʇ ǝsɹǝʌǝɹ]

Originally posted by ice:

blue sorcery reduction
when that don't work farm treasure

Others said it was a special action at sorcery speed, not a sorcery. Can you confirm if sorcery cost reduce works or not?

[Rakah]

Originally posted by Traumaturgy:

Marina Vendrell - she can lock/unlock your rooms. But she is all 5 colors to play.

Use the green room that makes mana all colours or use the creature that spawns all colour lands when it enters and attacks