The Demon Cycle book 2. A lot of real fucked up shit happens but it's not gratuitous in description and the world and characters are interesting. At night humanity is plagued by demons, which seem to be impossible to kill except by trapping them and exposing them to the sun. They're held at bay only by wards, a mostly defensive magic system of glyphs. It's not uncommon for the wards to fail on some way, due to the imperfection of the warder, poor maintenence of the wards, or some mistake to mar them.