Undercroft

In the Death's Head Orchard, the Craven Court is safeguarded by the Circle of Dawn, whose magical seals ward off entry underneath the ruins.   This is partly to keep nosy visitors from trying to sneak in an audience with the Crestfallen Prince, but the most pressing reason is that the Undercroft, as the place is referred to, is not safe to enter without extensive foreknowledge of its workings.
 

Dark and Dreary

The first thing that those entering the undercroft tend to notice is that the darkness that rests in the hallways that stretch impossibly far is so dense and overpowering that it seems like it is actively resisting illumination.
  But light is of utmost importance to any would-be-spelunker of those inky black corridors, as should darkness become absolute, the undercroft changes. If a torch is allowed to go out, the darkness swallows everything and those who were together will find themselves separated by vast distances in the blink of an eye.
  Trying to rely on one's memory is useless, as the walls will not be where they were just moments ago and should illumination remain absent, those lost in the shadowy corridors will begin to hear things. Scraping, running footsteps, distant wailing and unintelligible murmuring will drive those unlucky enough to be stranded in the undercroft into a panic, and they will most likely start to frantically move in a direction, touching the walls as they go.
  Invariably, these lost souls will come to find a small pinprick of light in the darkness, distant at first. As they move closer, they will find that it is a doorway and, when they look inside, they will see a seated skeleton clutching onto a crown, illuminated by the thinnest ray of light from some unknown source.
  More often than not, the lost will make the final mistake of their life and enter the room, leading to their near instant death as they age extremely rapidly and fall to dust in a matter of seconds. This grisly fate is brought about by the curse of the artifact the skeletal figure is holding onto, known as the Forgotten Crown.
 

Seek and Find

The seekers of the Circle of Dawn are constantly mapping out the Undercroft, trying to make sense of the layout of the place, but it truly seems like the entire composition of those labyrinthine halls is scrambled the moment any light within is snuffed out. Alternatively, it is the locations of living creatures within that are scrambled, which would perhaps be easier to believe than the entire structure changing shape.
  Despite these difficult circumstances, the knights have devised some means to combat confusion should they be lost in the dark. A system of wall markings that indicate both the direction to the throne room and the exit staircase has been invaluable in retaining seekers that would otherwise have been lost to the darkness.
  Each new arrival to the court is instructed to make as much noise as they can should they be separated in the dark, so as to make relocating them easier for their comrades.
 

Prince of Darkness

When questioned about the Undercroft, the Crestfallen Prince has thus far ever only responded with the word "Prison". This has been taken to mean that the Undercroft has been deliberately designed to be the way it is to keep something imprisoned.
  But is that something the Prince himself, the crown or something else entirely? Could there be something lurking the umbral hallways that the seekers have yet to encounter?