1 - The missing villagers of Tar

You follow the tortuous tunnel upward on something like 40 feet, and get the general feeling that you must be some somewhere above the copper room because of the very strong metallic smell around you.
At some point, the tunnel gets a bit larger and opens on a minuscule natural room that must be 5 by 10 feet. There's a tunnel above you that goes straight up, with some water dipping from it, and the tunnel you were in continues across the "room". It is large enough, though, to stand up and swap positions if needed.
The spiders continue to press on, and only Mee'haïl stands between you and that massive swarm. Sedror, you get in there first while Tianni does her best to wiggle in the tunnel with her heavy armor. What do you do?

Mee'haïl avdances a bit slower than you do, being busy fighting for all your lives.

As soon as Mee'haïl enters the larger part of the tunnel Sedror, who has been waiting for him with a flame in his hand, shoots it past the barbarian and right into the spiders... and the oil! The flame hits the ground, burning some spiders in the process, and then there's a big WOOF!A bright and hot fire start where your companion was standing a second before. You hear spiders shrieking and kill those who cross the fire to end, burning, on your end. The fire radiates a welcome warmth into this dark cavern, but also gives off a thick foul smelling smoke. Most of that smoke goes up in the damp tunnel, but some of it goes your way. You can try to resist it (CON save) or hold your breath until the fire stops (standard rules).

The dwarf's plan is surprisingly effective and, even if Mee'haïl suffered some burns in the process, the whole group is probably relieved to once again put fire between you and the spiders. You quickly cross the natural room to squeeze once again into the small tunnel.

Mee'haïl, you see the reassuring light of the fire for some time, until the tunnels makes enough zigzagging to hide it entirely. Then, unless someone provides light, it's pitch black again and you must rely on your other senses.
Tianni, you spot as you advance in the tunnel that there are spider tracks in this tunnel. Not a lot of them, but it is definitely used at least daily by big spiders. There also are cobwebs, but of a kind that matches "normal" spiders: being first, they slowly gather all over your armor and regularly get caught in your horns and hair. It's uncomfortable, but not enough to slow you.

You continue to advance in the tunnel. There are passages here and there that go up and down, but they are way too small for you. You continue to follow that path for a while, going up and down and starting to wonder if it even has another end. Those of you who are not used to narrow tunnel start to be uncomfortable, then almost claustrophobic. Meeting one of those big spider things in here would be a disaster...

But at some point Tianni spots a large passage one your right side. You can hear humanoid voices, probably coming from that opening. As you get closer, you can see that part of the tunnel collapsed into some kind of cave and that someone seems to be giving orders. You can't discern what is being told unless you get closer, but if you do so you'll need to be quite : you don't want to be spotted in that position!

The tunnel continues after the opening, going up and on the left.

Mee'haïl lows his torch down, making a low but warm ambient light in that cold tunnel. You are unable to discern any kind of light around, though.