As the key failed to fit in the hole.
Undertale locked door.
If used during the fight against mettaton ex the following text displays.
However unlike the snowed inn the money is not returned to them.
First you have to get the key to sans room.
Cinnamon bun reward.
Frisk do not let them in.
Nothing belongs to me.
You used the mystery key.
If the mystery key is used on the mysterious door it reads the following text.
Sea tea reward.
The door which bears the delta rune is surrounded by glowing mushrooms and floating particles.
To do that you have to save just before he judges you and then reload several times until he gives you the key.
Handing over any of the listed items rewards a response and in most cases an item.
You used the key the lock clicks.
The mysterious door is an area found in snowdin forest south of the right side of the room with the icy x s and o s puzzle.
Anyone that s started up undertale for the first time will encounter a mysterious locked door early in the game s snowdin area.
There is a dog behind this door.
Nothing will open it not even the expensive mystery key item.
That key will open the back door.
The protagonist can sleep in this room for 200 g yielding a similar effect to resting at snowed inn.