Daedric God of Schemes Molag Bal is the chief bad in The Elder Scrolls Online: the latest video from the Bethesda Blog reveals his own little realm of Oblivion: Coldharbour. Take the tour in the video below.
The frigid looking plane is explained by Lead Loremaster Lawrence Schick to have been linked to Tamriel by Molag Bal by vast sky hooks known as Dark Anchors: only the Soulless One (you, and the million odd other players) can stop his devilish plans.
Whilst you're exploring Coldharbour you'll discover why Molag wants to enslave Tamriel, and also why he has your soul stashed away in a special jar. Or something like that.