Illusory Dark Labyrinth

Illusory Dark Labyrinth is an area in B3313.

Description
It takes place in a large, dark, creepy and rusty labyrinth, shrouded in darkness. This location hosts the Core with suspiciously convenient arrows on the walls that point to the goal. Fast Travel is unavailable here.

After enough stumbling in the dark, the player will make it to the checkerboard floor room where the Core rests. The closer, the more nearby textures will become buggy and the message "DESTROY IT" will appear. This core is a trap, however

When the Player comes very close to the Core, everything will descend into darkness, and the Core will disappear. But in the distance, the old familiar Textureless Mario is already rushing towards the player...

Origins
It appears to be an original creation.

Sounds like the Haunted House theme from the Vanilla Game OST.

Plot meaning
It is likely that this place was intended for AI tests. But suddenly something went wrong there and this place suddenly became gloomy, dark and quite dangerous.

Leading here

 * Personalization Chamber: With some probability, you'll get sent here.