Travel back to the Wilderness, Underdark, Mountain Pass is ended ONLY by enetering Shadowfell, i.e. 5 minutes before ending Act 2.
IMO one of the mistakes of the game.
BTW - in one playthrough I raced to Moonrise Towers - ignoring the Druid verus Goblin feud - to recruit Minthara. The game went bonkers when I began to kill everybody in the Goblin Camp ... Minthara went hostile on me, then changed her mind, I killed and rezzed her, got attacked again, moved my camp to Mountain Pass, she was still hostile, so I kiled and rezzed her again ... it was a mess
