I finished Avanchnzel (returned the lexicon, got the buff) but there is an area still to clear that I can't get to. Towards the end in the boilery, there is a grated floor with a few mobs beneath it. It look like you have to get to it through a barred gate, but I can't figure out how to get past it. There are no levers or anything in sight... I've been trying to figure it out for a while to no avail.

Is there a traqezoidal table like structure in the middle of it with blue-green gems embedded in the top? You can get access to that and lower regions during the main quest.

Yea I have the attunement sphere for those that go down to Blackreach (if that's what you're talking about) but that's not here, just a barred gate with no obvious way to open it.

Let me run down there and check to see if I can find where you mean. Ah yeah I see what you mean - I think those mobs are supposed to spawn on TOP of the grating but I'll check around to see if there's a way to get down there. I just think its supposed to be a space for piping and ducts that looks cool and not a place where players or mobs go. The spiders though may be small enough to get down there which is bug in the level design - or they could have just spawned through the floor which is a collision glitch.

Yea that's what I thought... though it's odd that there's a gate there. I wonder if you were supposed to be able to go down there but they forgot about it and left the gate?

So I turned off clipping and poked around down there and yeah that's just an area full of piping to provide atmosphere/for looks. The spider does appear to be supposed to spawn down there but there's nothing else down there (guess the spider was probably working on the piping). The gate with the bars does seem like the kind you can normally open but its not (probably should have chosen a more obvious non-openable door so people didn't think there was something in there.)

You're not missing out on anything by not going down there though so don't worry - no gear, loot, or anything except for that one spider. I think it was just a bad choice for that object - the unmoveable dwemer fencing/grating material would have worked better.

Sweet, now it won't bug me anymore lol, thanks!

Avanchnzel somehow became 50th cleared dungeon to me. I know it, because after finishing the main quest I got the Delver achievement. Still there's no "Cleared" label under the Avanchnzel on the map, so it's just bugged. Don't worry, you all got it cleared already - it just never says so on map.Right after finishing Avanchnzel I ran thru all the map several times - there're exactly 49 locations with "Cleared" label.