The Vault is a medium-sized area that starts off as a large hallway that gradually gets bigger or smaller depending on the player's current direction in the room in front of the vault. The Vault can be entered from the large door with golden-like chains, opened with an Ancient Key, in The Grand Hall.
Inside the vault area, the Giant Ratfolk can be found sitting on a large object, telling the player about how the vault splits up the nightmare from the dreamers. Speaking with the Giant Ratfolk will trigger his message that the players should attempt to collect all the gold in the Nightmare, and remove the majority of the Rat Tokens from the Nightmare.
Once the players had collected enough Rat Tokens (500+), the Giant Ratfolk will state that he had made a breakthrough and had been waiting for the player's return. The Giant Ratfolk will imply that he had figured out the mechanisms of the vault and it requires two things to open it, the Dark Marble and the Light Marble. The Light Marble can be obtained from The Grand Hall's hidden key door (The Lost's boss), and the Dark Marble can be obtained at the End of the Road by listening to the three songs from the Journeyman.
After the players had acquired the two marbles and opened the vault with the Giant Ratfolk, the players will notice that the floor appears to be made up of hardened acid, and on the other side of the pit is a door with a red symbol above it, similar to the one seen in The Hidden Library. Attempting to open it will display the message, "Locked by Time". As of January 18, 2019, the door can be entered, leading to the Waiting Room.
The players will receive the Nightmare Visage from the NPC after completing the scenario. Once the players had exited The Vault, they may interact with the Giant Ratfolk a few more times to activate a side quest to collect every single Rat Token in the Nightmare, worthy of the player's time if they put a 'little' effort into it. Once the players collected every Rat Token in-game and hand it over to the Giant Ratfolk, the Giant Ratfolk will reward the players a Fantastic Ratboy, one of the collectibles that players can wear for vanity, and is required to complete the Itempedia of the Nightmare. The collectible will produce a swirling aura around the character once it is equipped.
- Unfortunately, The Vault does not contain any gold/rat tokens behind its door.
- It is one of the few places where something special occurs after fulfilling certain requirements.