The Veiled Prophet (released in 2007) is the eight book released for Diablo and the third and last book in the Sin Wars trilogy. Unlike all other books written for Diablo, these books are not standalone releases and must be read in order if you want to understand their story. We have already covered the first book over at Diablo Birthright and the second book over at Scales of the Serpent. Like the previously mentioned books, The Veiled Prophet is written by Richard A. Knaak.

By the time you reach this book, Uldyssian will have already destroyed the Temple of Triune and has now set his aim on the other side of the coin, the Cathedral of Light. Uldyssian and his followers have started to travel to Kehjan City where they seek to unite the Mage Clans against the Cathedral of Light. On their way to the city, The Edyrem (the new name given to Uldyssian's band of followers) met a very influential merchant and asked for his help in order to get an audience with the Mage Clans. Since by this time The Edyrem grew to over a thousand, only Uldyssian continued the journey to Kehjan City along with the merchant and his guards to avoid getting mistaken for an invasion.
Things don't stay on track for long however, as Uldyssian and the merchant are attacked by a mage and his servent. Uldyssian was contained in a binding spell while the others where killed, and he was then transported to the mage's sanctum beneath Kehjan City. The plan was to frame Uldyssian with the merchant's murder. His monstrous servant however, had other things in mind. When the mage leaves to meet with the Mage Clans, it is revealed that the servant is actually is actually Malic, the loyal puppet of the Primus that Ulyssian had previously killed during his attack on the Church of Triune.
Malic's malicious plan was that he took the form of a disfigured man to serve under the Mage Clans, allowing him to reach his target goal, Uldyssian. Malic actually possessed a fragment of the World Stone that allowed him to transfer his soul into new bodies. These bodies where frail however, and only lasted days at most. Uldyssian's body would allow Malic to have a permanent host.
The book continues on with Uldyssian being constantly plagued by Inarius who sent many people to spread spread lies about him, framing him for many innocent deaths. From here on in, the book gets really intense with things such as the Uldyssian and Inarius fight, the threat that Malic could be anywhere, the fight at the Cathedral of Light, and many more.
The ending is one of the best parts of the book, and one piece of lore that everyone who plays Diablo should know. The armies of the High Heavens and the demons of the Burning Hells finally invade Sanctuary just as the battle was coming to a close. I won't spoil what happens next however, but it basically explains how Sanctuary still exists today, and how close it was to being destroyed.
The Veiled Prophet can be purchased for less than $10 in standalone format:
Or as the full Sin Wars trilogy: