Nightmare Fiends

Nightmare Fiends are sickening and horrific abominations usually formed from the most corrupted souls. Their misshapen and hideous bodies makes them easy to recognize. All Nightmare Fiends are extremely dangerous, making them deadliest of all Fiends. Their bodies are usually riddled with natural weapons like claws and spikes, or have developed toxic chemical weapons designed to slow or immobilize their prey. In addition, these Fiends tend to be the most intelligent of the three categories, able to strategize and adapt mid battle to their circumstances, sometimes evolving on the spot to suit their needs. Fortunately these Fiends tend to be the most rare of all Fiends. These are also the only Fiends known to be capable of taking on a humanoid form as well as utilize manmade or improvised weapons and other sophisticated resources. There are no set variety of nightmare Fiend, as there constant transformations make it hard to pinpoint them into categories.
Some Nightmare Fiends also are able to access the memories and emotions of the souls within them, and generate speech through mimicry of their surroundings. They are also clever enough to leave their prey alive and suffering, leaving them free to call for help and attract other prey. But do not rush to their please and cries for help unprepared, or you will likely be walking into a trap.