From Amazon
Shadowkings, Michael Cobley's impressively unpleasant first fantasy novel, takes place after the worst has happened; the invading forces of the evil Lord of Twilight have burned the tree which gave the wizards of the Khatrimantine Empire access to the roots of magic, and shattered civilisation into anarchic fragments. Things are about to get worse--the five warrior-wizards who between them carry the parts of the Lord of Twilight have rediscovered who they are and are coordinating the mopping up of the last bits of opposition. Of course, things are never that simple: demonic generals with a nasty taste in mayhem cannot be relied upon to accept personal dissolution, for one thing, and fur-clad barbarian hordes tend to want to get something out of evil in the way of land and loot rather doing evil for its own sake. And new imperial heirs with magic powers will keep turning up...
If it were not for its unrelenting bleakness, Shadowkings would be a fairly standard story of apocalyptic evil and heroic good--Cobley has a sense, however, of how bad a battlefield or a ruined town smells, and his dark magic is appropriately sinister. --Roz Kaveney
Book Description
Sixteen years have passed since the evil deity, the Lord of Twilight, was shattered into five hosts, souls destined to become the Shadowkings. Now the Shadowkings are compelled to return the Lord of Twilight to his fleshly being. Many lives will be changed forever as battle commences yet again.