Dark Enlightenment: Book Four of the Dark Pilgrim Series. Dark Pilgrim Series, #4

The end is near. Hundreds of planets have been laid waste by the Drek and the virus. The Restoration begins in earnest its campaign to destroy The Church of the Blessed Prophets. Lord Comte Mishi's rebellion against what's left of the Imperium gains solid ground as the Lord Cardinal Nerodia presents the Lord Marshall Bhagavan in chains. Ailanthus' band of friends grows smaller and smaller with death, betrayal and self-sacrifice, while his responsibilities grow larger and larger and he learns fully the distorted history of humans and Dwad-Mehstiv and what he must do to save the last remnant of humanity.
Thus continues the saga of Ailanthus and Tethys, two friends caught up in a universe that wants more from them than they are willing to give.