My excperience with Book of Ebon Bindings is thus I feel that it is one of the greatest "in game" pieces of role playing material written. The book gives all of the background of the religion of Tsolyánu & the 48 planes beyond. This isn't for the faint of heart. Those who aren't mature or don't understand should probably stay far away. This book has an emphasis on demonology, summoning, demon abilities, and banishment rituals. No game mechanics. Later re-printed in a larger format, with a black cover, by TOME.
Red Cover Version of The Book of Ebon Bindings (Imperium Publishing Company)
Demonic Powers presents - Demonic Powers from the Book of Ebon Bindings is a handy reference to all of the abilities of the Lords of the Demon Planes. There is no need to go flipping through your books to find the definition of abilities such as “Abcission” or “Colliquation” or even “Metagrobilisation” – these powers are listed and defined, along with all of the rest. This article is a necessary reference for game masters and players alike and is useful for every Tékumel campaign. 6 pages. This book is free Here
For those running a Human Space Empire Game or Empire of the Petal Throne this is a must have. The sheer detail is incredible & it could possibly be used for other systems & varied encounters. The level of work that went into this book is massive but the book itself isn't. The adult nature of the book can make it seem well odd as it piles weirdness on top of weirdness. The only other game book that has this level off oddness is Carcosa.