Apotheosis is a dark fantasy, story-rich, open world expansion for The Elder Scrolls V: Skyrim set across the 17 Planes of Oblivion, and 'Dreamsleeve', in an echo of a fallen world.
"Once the sword arrived in Vile's realm, Umbra escaped and cut away some of the Prince's power for itself. Umbra took the form of a dark being, in the shape of a man but with eyes like holes into nothing. The Prince did not want Umbra to escape with his power, so he changed the walls of his realm, essentially trapping Umbra there. Using his stolen power, Umbra was able to conceal himself in one of the cities at the edge of Vile's realm, fearing that Vile would return him to the sword. In the early Fourth Era, Umbra was attracted to the influx of souls coming from the rift in the realm caused by the first ingenium, which held Baar Dau aloft above Vivec City. Casting a fortune, Umbra learned that the rift would one day become wide enough to throw the Umbra Sword through, lessening the threat posed by Vile. That day came when the ingenium was destroyed; Umbra threw the sword to Mundus, while at the same time Sul and Vuhon, two Dunmer responsible for the ingenium, were sucked through into Clavicus Vile's realm."