The fourth T2G mission, which was to be set in necromancer controlled territory in the mountains, was to be an undead/horror mission featuring craggy cliffs dotted with haunted towers. This mission was sadly lost. There was also supposed to have been a Hammerite mission added to the mix, but from what we have here it looks like something changed along the way, some information is wrong, or whathaveyou. In general I wouldn't consider anything I've said here the official word on anything.
Edit: A little more on that Hammerite mission... The idea was that Garrett gets a Hammerite priest drunk in a bar and gets him to spill some info about Karras's past within the order, and he then has to go follow up on it by breaking into an old run down Hammerite church.
http://www.ttlg.com/forums/showthread.php?t=108070