The sextant points us behind the glowing mushroom in the back of the cave. There is a small water flow that is inhibited by it, as well. So, Cap and I start to hack our way through. While we're doing this, I take a closer look at the smaller variety we're cutting through. It's often used in potions, poisonous when raw, and often grows near semi-sentient varieties. As that last trait starts to politely clear its throat in my brain, the large central mushroom wakes! It "semi-sentiently" turns and attacks. As it stands, it releases the water it's been holding back, which pushes us a bit. I hold my ground and hear Her voice: "I will protect you." I don't think I'll ever get used to that. After a fierce battle, with the captain actually dropping once, she delivered the killing blow, stabbing it through the head.
During the fracas, Aerathor informs us of two inbound individuals. I gather they meant to loot previous non-returnees (and perhaps us), but once they were warned of the basilisks, they rethought their approach and, I think, are trying to lure them out the center cave mouth. At the very least, they may be distracting enough for us to get out unscathed (once we find our objective).