“Humanoid” creatures native to the Plateau of Leng. They have such disturbing anatomy that there is a 50% chance that they can ignore critical hits or precision damage. Their otherworldly teeth and tongues deal 1d6 Dex drain with each bite. Immune to poison. Cold and electricity resistance. Spell resistance. Do not breathe.
They maintain a spiritual connection to Leng that grants them fast healing. If killed, their body dissolves into nothingness, leaving behind their equipment, and they then reform, fully healed, in Leng.
In Chapter 78, as Weiralai revealed her true form, the nature of the physical structure of Denizens of Leng was revealed to be even more aberrant than their outward appearance would hint at. They have goat hooves and are taller than they appear. They possess more joints than normal humanoids, and their internal makeup seems to consist entirely of mouths, teeth, tongues, tentacles, and tubes, which they can unleash on victims as a devastating form of attack. As creatures of Nightmare, they do not occupy physical space in the Material Plane in a manner that conforms to expectation. The appearance of them is enough to drive mortals mad.
First Reference: Chapter 62
Other Notable References: Chapter 78, Chapter 145, Chapter 146