Dungeon Heart: Hell Gate (Dungeon Heart, #3)

Hell hath come and the horde rides in its shadow!
In the high stakes world of dungeon keeping, the price of success is the avarice of your peers. Smit has defeated those who would take over his home, and all he wants is a bit of peace and quiet with his family. But alas, fate has other plans in store. A demonic lord from the deepest pits of the underworld is ready to unleash every corrupted spirit and demon at her disposal to capture him.

Forced to fight an ancient entity that weaves plans within plans, Smit will have to use all his inventiveness and cunning to lure the demonic horde into a trap. By pushing himself to his core's limit, he might convince others this rock is too tough to crack, but if he fails, an eternity of darkness and servitude awaits.