aramis erak
Legend
All the paths are under 5' wide. Visibility to the prisoners is blocked by the large stalactite (and by elevation change). The access to the large stalactite provides a room that can be maybe 4 people... it's a choke point for sure... but a sorcerer or wizard can use a spell that doesn't require materials to take out them. A first level can do burning hands (L1, VS), or create flame.From what you have posted I am going to disagree with you here.
A fighter can do 3d6, dex save for half, by forcing them off the walkways into the web via grappling, or in other areas 6d6 by forcing them over the cliff to fall 60'+...
The drow won't readily do this - slaves are profit, after all. But PC's can and should make use of the lack of surround to chuck drow over.
The spiders can be hurt easily enough. Apply a flame to the web - the web burns the spiders, AND they fall 30+ feet (for another 3d6.
Only one area of really open ground exists in the complex - in front of the drow barracks. Those rooms are SMALL...
Note that, if starting from first level, PC's shouldn't try to break out 'til second level...
Also note - the real threats are Ilvara (who can insect swarm for a lot - provided she can avoid melee), Asha, and the quaggoths. The Drow Elites shouldn't be together - they should be serving as officers. So, 2 resting, 2 on duty, 1 on patrol and 1 in Ilvara's boudoir...
Also, Ilvara should basically ignore things until another drow comes to get her lover.
Note also - it's kill 1 prisoner per rebellion - but those who take out lesser drow DO get XP for them, even if the PC is beaten down.
Now, it should take a few days to get reinforcements... so even tho' Ilvara can send for them, losses shouldn't get immediately replaced.
Oh, and the quoggoth are important for another reason - they can climb the walls and attack vertically, allowing for surrounding the PC's - only Ilvara can do similar amongst the drow there.