The Great Ordeal is out today (well, 29 September, which is in an hour or so) in the UK and Commonwealth territories from Orbit. The book was previously released by Overlook Press in the United States in July.
The Great Ordeal is the third and penultimate volume of The Aspect-Emperor, and the sixth novel set in Bakker's Second Apocalypse mega-series. The next novel in the series, The Unholy Consult, is already complete and has a semi-firm release date of July 2017.
You can read my review of The Great Ordeal here and catch up on the History of Earwa with my five-part catch-up series here.