The first door you'll find leads to a safe area called The Arisen's Refuge. Repair the rifstone there and rest as necessary. This is one of Barroch's spawn points. The are enclosed cells here that you can open with the help of skeleton keys. Explore the area and kill the possessed pawns and an eliminator in the tight corridor of the dungeon cells. The next room also has a lot of enemies; just make sure to take out the sorcerers and mages first. After looting the chests, take the ladder to the north down and follow the spirit. Go downstairs the pitch black pit until you reach the bottom. There's a lot of leapworms waiting below so be prepared.
You're now in the first level underground of The Bloodless Stockade. Check the area past the broken grate to the north to find a chest possibly containing a Bitterblack item. There's also another chest east of the beacon. Continue southeast and make your way to the exit. Take note that the Reaper may appear here as well as an Elder Ogre.