The Fourth Tier - The Underworld Series, #1

The Fourth Tier is the first book of the Underworld series, a spin off from author Penn Fawn's Necropolis dark fantasy novels. For the deceased, the underworld represents a terrifying awakening. It is where men who believe after they die they will sleep in eternal peace go, as opposed to being in a state where they are forever at rest. The fourth tier is the deepest, darkest, most terrifying place in the afterlife where only the most unfortunate souls might be downcast.
It is home to the master of sorcery and dark arts, the necromancer, and his alliance of beasts and the undead. This is precisely where our protagonist, Hespatia, and her peers who've fallen from grace find themselves. A desperate struggle to try and find a way out is their fare in this place filled with horror, and abound with curses and danger at every corner that the necromancer instills to keep all who try to escape in line.