I have two flying fortresses left, but can I do the last part of the Hall of Echoes quest in Broken Valley and then return to Orabus Fjords after that and finish the fortresses? Or does doing the main quest set you on a different course?
When you physically enter the Hall of Echoes you can not return, but just completing the quests isn't a problem, and you can continue to go back and forth between available areas.
