1 - The missing villagers of Tar

Cobwebs burn behind Tianni as Mee'haïl advances with his torch in the narrow passage. The big, gelatinous, giant web strings continue to run above you until see one of them attach to something. Unlike the other webs you saw up to this point, this one is very hard to notice and Mee'haïl only saw that one by chance. A bit late, though, and you see Tianni stumble on something.

Tianni, you feel that your left foot got stuck on something and you lose your balance. Make a DEX saving throw DC 15 to stay on your feet!

Tianni you lose balance and fall down but, to your surprise, you barely hit the ground. Your fall was stopped a few inches above the dirt and you seem to be floating mid air... until you notice that you are unable to move freely. It takes you a second to realize that you walked on a fresh and sticky web and fell onto it. And now you are stuck on it, face down, in an awkward position.

Bug, as you look around to check for incoming spiders, you notice that the vibrations from Tianna's web are passing through some kind of big semi-transparent web string above you (the one spotted by the rest of the team earlier).

Some strings seems to break as Tianni wiggles but she ends up more stuck than she previously was, and start to feel a little bit like a fly caught in a web that makes its situation worse with every move...

Bug, your intuition was right : you hear the typical hissing of giant spiders responding to their catch! They are far enough to be barely audible... but close enough to be heard!

Edit: you hear that sound echoing from somewhere east

Due to the moisture of this kind of web, you have a hard time trying to set them on fire. But at some point, one of the strings catches fire and burns with an unexpected intensity. Fire spreads slowly on the web but it will certainly hurt Tianni if it reaches her, which should happen within seconds.
Tianni, you've got one last saving throw before the fire reaches your right leg. Entangled like your are in the web, it won't be an easy task! One good thing, though : the fire weakens the web, and you are no longer at disadvantage for your roll.

Tianni, that will be a STR saving throw with advantage and possibly Bardic Inspiration VS a 20 DC.

The web seems to burn pretty slowly, you don't know for sure how long it would take for the fire to extinguish. So it would be safer to cut her free. You can achieve with your next action but you'll have to endure some small burns too.