User blog comment:Blood Reaper/Todd Howard Hinting at Future DLC's and Patches/@comment-2252876-20120223032151/@comment-4118895-20120224001027

I believe the DLC your looking for is a land called Coldharbour. It is the twisted and dark version of tamriel where everything is basically evil. As quoted by the wiki page, " Coldharbour, the plane of Oblivion that is associated with Molag Bal. Resembling that of Nirn, but the ground is nothing more than sludge, the sky constantly burns, but yet the air is beyond freezing. Even an alternative Imperial Palace, as described in 'The Doors of Oblivion', is known to be there, but dripping with blood and laden with corpses. Surely one of the most inhospitable realms of Oblivion. "