- being knocked upside down and desperately shaking their legs trying to restore;
Holy Godz, I fear any insect doing that, let alone the spiders. I can kill them easily while standing still, but when they're agitated with all those creepy legs in the air... disgusting!
- trapping people/creatures.
We already saw a trapped Dunmer, so this is definitely in, but would be cool to witness something like that in real time, you enter a dungeon, hear fight noises from below, advance cautiously, then suddenly the silence. The painful, horrible silence. You sneak into the hall. Blood and webs everywhere. The paralyzed adventurer is still alive while being "packed", you can tell by his terrified convulsing eyes....
For the emphasis, I would like the spider dungeons to be really really dark. Pitch black. Torch or no see.