This is really minor what with all the bugs related to the expansion, and may not even be a bug. I think I have a side-quest monster spawned behind a locked gate that I can't unlock because I took the other choice at the point where you unlock either one gate or the other (usually XP vs. treasure, more or less) back before I initiated the quest. (And the lever disappeared, as usual.) Attached is a cropped screenshot, with the map blown up as big as possible to show where it thinks the surviving quest monster is. I don't think this is related to the expansions, but in case I'm wrong, I have all of them installed, running off Steam. No other problems so far except with achievements.
This is where the dragon's breath or other magic spells are your friend. ...or, since judging by the screenshot you have the fungus friend, just spawn him in there and let him go to town!
This is where you start thinking and stop constricting yourself to your character's build. You can use anything that is ranged to kill that, or you can use a movement skill/item to get there and kill that.
Yep, fungus inside the gate is the answer there. Alternatively, look for items that push objects or destroy walls...
