Eight Rivers of Shadow (13 Days of Midnight #2) by Leo Hunt
In a high-stakes sequel, reluctant necromancer Luke Manchett must call upon the most wicked and eerie ghosts of his dispelled Host to save two innocent souls.
It’s been a few months since Luke Manchett inherited a Host of eight hostile spirits from his dead father and made a deal with the devil to banish them. Luke’s doing his best to blend in to the background of high school, to ignore the haunting dreams spawned by his father’s Book of Eight, and to enjoy the one good thing to come from the whole mess: his girlfriend, Elza. And then it all begins again. Ash, a strange new girl with stark white hair, requests his help—and his Book of Eight—to save her twin sister, who was attacked by a demon. Ash knows a lot more about necromancy than Luke and seems to know what she’s doing, but can she be trusted? As Luke is drawn into a spiral of ever more dangerous favors, he finds himself not only summoning the deadliest members of his father’s Host, but returning to Deadside in a terrifying quest to save what he holds dearest—or die trying.