Dirge of the Dead

Nightmare magic can kill an arch demon. It cannot undo a grave.

Oxivius has a plan for that, and the plan is a heresy. Go down into the infernal realm, take a soul off the ledger, and walk it back out. The Council of Magic calls it a crime against the natural order. Heaven and Hell agree with them, which has not happened in four hundred years.

Something comes back out through the Necropolis gate. Burned down to the tattoos, regenerating, and carrying the dead with it. Nobody expected it to be him.