I thought its that guy too but i mindreaded him already and got the key to his cellar with the Alchemist tree .i did try to mindread him again after i found that hatch but i couldnt , also there was no new option to ask him about the hatch ... so i guessed that cant be him .
Did you mindread the tree?
bellegar ... yeah but already defeated all his broken valley summon challanges, did the maxos temple -- but only to the point where i got the acces to sentinel tower and i still couldnt scare the sosostra away .
Have you checked to see if she has any more prophecies for you? I only ask as I'd failed to do that myself; if she really has nothing more to say, I guess it's just "one of those things"...
