The Apostate Auguries are a collection of prophecies from Tryphosa, a powerful Malkavian seeress. They detail the rise of a a great Shadow from the Abyss and of the escape of a great beast imprisoned there. This beast will then attack something, researchers believe that it means either Son or Sun. Some of this points to Gehenna and the rise of [Lasombra].
The book is currently in the possession of the Akritai, an order of Hunters that destroyed Tryphosa in Czechia. Their researchers, however, have great difficulty in deciphering Tryphosa's mad ramblings.