https://www.amazon.com/dp/B0FZ45WC33/
This is the first book in the Psalm of Stars Series.
After a thousand-year conquest, the Nikolova Clan now rules the vast Empire of Andaverld, from dark valleys in the west to the shores of the eastern sea. Within its ancient vassal kingdoms, legends tell of secret temples lost to ruin, daemons that haunt the tall mountains, and gods that once walked the realm in the dawn of time. Struggling to keep a fragile peace in the name of its great god Nikōs, the Empire has declared any speak of these myths and legends heresy of the gravest degree, and anyone found with their relics a traitor to the Crown and Church. Amidst the rise of insurgents and infidels, the Emperor has employed the Reapers: a company of assassins for hire said to practice dark arts and perform blood magic on their felled enemies.
Here a noble house with a mystic history faces a trial that threatens their rule; a scullery maid finds treasure of unparalleled value; a skeptical Magister battles enemies from within the Imperial Court; and a jaded Reaper uncovers secrets that foretell the coming of a storm as cosmic as it is inevitable.