Portal to Misty Grove
The portal is located at the top of a flight of stairs guarded by a high level mage, e.g. an Arch Cryomancer, an Arch Electromancer, an Arch Pyromancer or an Arch Necromancer. There are also several other hostile mages off to the left of the staircase.
Although the portal is at the top of the stairs, its effect (teleporting the Dragonborn to Misty Grove) also affects a small room below the stairs. To loot the containers within, it is simpler to wait until after the episode in Misty Grove. Alternatively, the room can be looted before ascending the staircase and activating the portal.
Naris the Wicked's torture room
This room is guarded by the hostile mage, Naris the Wicked. Inside are a number of burnt bodies.
Items of Note