The giant studies the situation for a moment... then has an idea. He saw Artan close his eyes to move down the hall, but Beshlog really doesn't want to go totally blind. So, he'll try another less-than-sane tactic... he's going to try walking backwards towards our goal.

Artan sits on the ground, closing his eyes, and waits. Nothing happens. Finally, he gets up and looks at Salastor, trying to gauge his behavior. Salastor's face is devoid of emotion, as he seems to be contemplating how to get to the end of the hall

Beshlog tries something different. He starts to walk backwards, and he watches as the party gets farther and farther away. Suddenly, he hears a far off "BOOM!" from behind him. I'm going to need a wisdom save to not reflexively turn around at the sound of the explosion. Don't worry, it'll be a low DC

Beshlog Wis save: 22

He manages to not turn. He keeps walking, until he feels heat on his back. The sound of crackling flames is behind him and growing closer. The heat grows more intense the closer he walks.

What does he do?

The party looks down the hall and sees fire starting to consume the portraits and carpet in the distance.

Beshlog will continue on his way, convinced that it's some illusion designed to stop them until such a point as it is clear that the flames are actually hurting him.

Beshlog keeps walking. the duplicity of this place had tricked him enough. he would not fall to its trap anymore.

Artan will copy and walk backwards. And because he's annoyed at this room, will knock portraits off the wall as he goes (especially any of himself) 

"What the fudge."  Ember says, also walking backwards.  She swipes a painting of herself with salacious content, cuts it out of the frame & pockets it.

Kordia watches as each companion turns and backs their way down the hallway.   With a sigh, she too joins the back track line.

The last to adopt this strange behavior, the last to even understand the problem, Flax suppresses the urge to complain everyone is acting weird and going the wrong way, but sighs and follows their lead, and walks backwards as well.

The other party members follow, copying Beshlog's behavior. They watch as the door from which they entered gets farther and farther away as they walk backwards

Beshlog keeps going, seeing his party members following. The heat grows more and more intense. He has to make a CON save, which I rolled in the game log, and managed to resist taking any fire damage. But, the flames do grow hotter, and the sound of burning wood, and the smell of burning paint both grow more distinct. Looking up slightly, he sees smoke on the ceiling.

Kordia feels the heat and smells the smoke.  Digging about in her bags, she pulls out a water flask and points toward the ceiling 'behind her'  Mage Hand . The flask floats up above the heads of everyone and begins spraying out it's contents splashing water about to help keep the flames at bay as the group travels forward backwards.

Kordia tries to douse the fire, but it doesn't have much effect. 

Does Beshlog keep walking?

Yep. He's gonna walk 'till he can't no more.

Kordia frowns at the lack of results with her water skin attempt.  Muttering under her breath, she will direct the skin back down so she can secure it to her belt.. to be filled at a future date.   A keen listener may hear some choice phrases in a variety of languages... which all seem to be invoking god directed doom on this crazy place.

"Flax, old man.  How are you holding up there... er, back there.   I really do hate this place,"  Kordia swears in Elvish.   
"Is it getting hotter in here or is it just Ember?"  

Passive Perception: 14

"Is this shit real or are we being jerked around again?"

Rollin' another CON save for Beshlog. He rolls an 11, failing and taking 5 Fire damage.

Beshlog keeps walking, and the heat now burns his back. The fire is real. Most assuredly.

Kordia asks questions as she keeps walking, one of which elicits a blush from Ember. And yes, it is getting hotter in here. No, the fireball throwing sorcerer is not the cause.

"Har har", Ember sarcastically laughs.  "Of course, I could cast a Fireball to try & burn away the wood fuel.  Maybe a True Strike to get around the dimensional effects.  If anyone thinks it would work."

"Ouch," Beshlog grunts... but he's not going to stop until he gets to that damned door.

Beshlog keeps walking. Let's see what he gets for that save (Whisker, if you ever want to use stone's endurance on this, just say so in your next post). Luckily, he succeeds (just barely though!) and takes half damage 4

Does the rest of the party keep walking as the first lick of heat begin creeping up your back?