The Black Moon Chronicles Vol. 21: Sic Transit Gloria Mundi

Although the One and Only succeeded in brushing Beelzebub aside, the gateway to Hell remains open, spewing forth endless demonic legions. And to make matters worse, Wismerhill was killed on the battlefield. All hope seems lost until, to the astonishment of his grieving friends, he brings himself back to life. But the empire will never be able to win this fight alone, for the unrelenting denizens of the underworld demand their pound of flesh and refuse to return to the depths of Hell without it.