Dominum Eterunus

The city floating above Slekul during the Age of Aether. It was said to have one day disappeared only to have parts of it start reappearing 50 years later bringing corrupted aspects from wherever it was previous shunted.
Adama received a vision of what we believe to be the city in Deep Beneath - Bismuth Abbey :
Adama, sword aloft to light their way, is hit with a wave of appreciation for the space and its history. He's struck by how the story of this space is the story of life, a story of preservation, and how he's glad that his friend made it down safe. How it felt good to enable that. He's also struck by the feeling that while the safety of his friends is fine, that feeling needs to spread. That life needs to continue. Briefly, he sees a large tree, beautiful and resplendent in life seems standing out amongst the lands around it which seem to be encroaching with death and decay. The marching encroachment of death seems not to be just an affect of the land, but a marching series of armies headed towards the tree. As they approach the tree rises and a city can be seen clutched in the large roots of the tree. A siege begins on the city, the tree seeming to guide one side a beacon of life and preservation. As the forces grow ever closer the tree begins to ascend into the sky, but tendrils of these army seems to grasp and pull the city down. Adama feels a final rush of life, the need to survive and preserve, as the tree and the top half of the city disappear. The armies below crumble as death and the vacancy of life takes hold of the land and in the rubble of that city Adama sees what looks like a familiar skull from the rocks that remain.