The chance for the dungeon to appear seems to be around 1:7 and probably spawns in either the West or North-Eastern portions of the map (where the khazra totem portal can spawn).
Enemies found here include:
- Dark Summoners & cultists
- Disentombed Hulks and
- Dark Berserkers.
There are a couple rare packs as well.
Upon entering the dungeon you will find Rike the Apothecary, whom upon helping him save his brother will give you potion(s).