[David Bofinger]

So the little ones are nuisances: if you don't see them you might step in and take some minor inconvenient injury. Unfortunately it's an injury that TFT can't easily describe, not sure how to address that.

The big ones will kill you if you fail both your IQ roll to notice and your DX roll to fall on your feet, unless outsiders somehow intervene. (It's not clear how ... do they have to jump in with you and make their own DX roll? That might be a way to find out who your real friends are.)

If you pass the DX roll you get 5/ST rolls to escape ... I'm unclear how often you're allowed to make those, perhaps the implication is once an hour? I would also imagine you could cut yourself free, assuming you have an appropriate tool, which I think nearly all adventurers would.

All in all it seems like an acceptable nuisance trap. But it's too realistic, and hence too passive, to make an interesting threat. There's also a good deal of ambiguity. To me the most intriguing thought is that it might be dangerous for friends to provide assistance. I would develop that aspect.