Said to be bound in human flesh, and if opened by a mortal, is known to cause the most intense and painful experience one can imagine. Before simply disappearing from existence. Containing the Rules for the Umbral Courts, personal details of unimaginable torture wrought by Zon-Kuthon himself during the Age of Anguish and finally, holy poetry and scripture on the essence of pain and torture. All written soon after his change from Dou-Bral to his current form. It was written in his own blood shed from the ritualistic torture that he used to twist and warp himself to his present form.
This is not a small book and acts as a infinite spellbook, never changing size from its formidable 10'x 5' proportions. It is located in the realm that Zon-Kuthon inhabits and is always within his sight in his throne room. It offers no real special benefits to travelers, but then again, no one has ever had it to study. And any knowledge is either ancient, or plain guessing.