Found in the Hollowlands, this location is found in Detyre, tucked away in the bottom corner of The Hollowlands. The location is visited towards the end of the Warsworn questline, after retrieving the Mystic Hammer remains from Eagonn's tomb.
You can visit the site earlier than this, however there is a fateshift door that prevents you from travelling through the dungeon fully.
While visiting the tomb with Gwyn Avry, she reveals upon entering that it was here her mother travelled to before disappearing. Her body is found in front of the sealed fateshift door.
The dungeon itself is very simple, with very few hidden locations throughout the dungeon, and a handful of chests.
It is also here that the Warsworn questline is finished, with the player being awarded the title of Truesworn, an honour only one or two people receive in a lifetime (This presumably means every 100 years or so)