Borimer tests his sword and finds that the flames appear natural. They do not appear magical but instead come from some gaseous fuel flowing up from tiny holes in the ground that are lit. The figure inside continues to call for help.
Listening to Tahldar, Borimer flies up, grabs Kahan, and takes him down the hole to the ring of fire. Kahan still holds the grappling hook.
Meanwhile, Shapfren and Leo start along the right side using the niches...both make it without any problems.
When she gets to the point marked "d", Shapfren sees that there appears to be another tunnel leading east.
Time holding breath: 30 seconds.
As Shapfren holds onto the handholds to avoid quicksand and looks east, and as Leo is not far behind him, they hear the cackling laugh, followed by another, just to the north of them. And that's when through the green sulfurous smoky mist, the two green-flamed skulls come into view.
You have heard the arcane stories of these flameskulls. They are evil, undead, and have at least two fire based spells they can cast. And casting a fire based spell in this highly flammable area would be potentially deadly.
But for now, the two flameskulls cast a spell that Shapfren identifies as the blur spell. The two skulls become blurry to look at, shifting and wavering.