Source: Nidal, Land of Shadows, pg(s). 57
The Joyful Things are among the most envied of Zon-Kuthon's followers—individuals who have undergone the Joymaking ceremony. These devotees voluntarily have their arms, legs, and unnecessary extremities such as eyes, ears, and other sensory organs removed over the course of a single night, believing that the less flesh a person has the more pain and pleasure they experience, and thus the more of such feelings they can channel to their dark god.
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