The Book of the Dead was an Ancient Egyptian book made of pure obsidian.
Known colloquially as "the Black Book”, the Book of the Dead contained ancient spells and incantations that could resurrect the dead and can summon the Warriors of the Book (Ghost Warriors). In the late 3000's B.C. King Ramusan protected the Book of the Dead in the Treasure Chamber in his palace to keep it safe form anyone taking it. Two thousand years later to keep it safe from interference from unworthy men, the ancient Egyptians kept the Book inside a statue of Anubis at Hamunaptra, where it was declared forbidden to use. In the late 3000's the Book of the Dead spells and incantations used to be useless unless you use the Eye of the Gods Medallion while reading it. A couple years later the Book of the Dead was fashioned so that only one with a "key" might open it: indeed, the Book had a small puzzle-box-like object that, when opened, acted as the key with which to open the Book.