As you walk through the cavern entrance from the Trampled Fields, and the darkness begins to close in on you, it will become your immediate priority to close your eyes as soon as possible. You will begin to sense a light touch your eyelids as you are forced to walk through what feels like smoothed-over glass. You will have to rely on the echoes of your footsteps to move forward.
Should you ever open your eyes in this layer, you will find your body is emitting a sort of bioluminescent light, which will reflect onto the cavern floor, walls and ceiling. The caverns themselves are made from glass and silver, which mirrors your appearance. You will not immediately recognize the mistake you made. As you look at your reflection, you will become more drawn towards it, unconsciously taking time to admire yourself. You won't even recognize the shapes behind you at first, because you'll be so transfixed on your own self-image. Their voices will whisper through your ears, urging you to follow them. They will promise to make you beautiful. You will follow them without question, into a segment of the caverns where the passages are narrower, and the surfaces are sharper on your feet. You will look upon the mirrors, and you will find your image has been changed, to match an idealized version of yourself. At this point, you will lose any will to resist the shapes and their influence. They will lead you further and further into the caverns, as the passages grow sharper and narrower. You will feel the glass stab the soles on your feet, you will feel the walls close in on you, you will crawl further through passages of sharpened glass and silver, and you will not care. You'll be in agony, but your desire to achieve perfection will be stronger. And so the cycle will continue, until you are nothing but a shredded, moving mass of flesh.
The shapes will prey on your natural desire to be desirable. They will prey on your ego and your sense of self-worth. This is why you must never open your eyes. They will speak to you, urging you to follow them, but you must not listen. You must move in the opposite direction of their voices. As you do this, their facade of kindness will slowly drop, replaced instead with a stream of whispered insults to take advantage of your insecurities. You will feel a natural urge to correct them, to fight back. You must not. You must ignore them, no matter how deep their words cut. Should you follow these guidelines, eventually, the light in your body will begin to fade, and so too will the shapes' voices. Only then will you be allowed to open your eyes, and pass through the rest of the cavern normally. Your exit will lie at the end of the final passage.