Well, the poison area is at the end of a long tunnel, I forget if there were originally trolls there. Its empty now since I've been there so many times trying to solve it At the end of this long tunnel is a junction that is impassable because of thick poison. Right there you can see two doors, both of which are locked, but you cannot do anything near those doors anyway because of the poison. I dont see any place to jump up, nor any levers.
