Marasatra lifts one hand for patience. “Before we bolt through that mire on blind luck, give me ten minutes to work a safeguard. I can ritually cast detect poison and disease—once it’s up, Ekko and I can trace the air for pockets of methane or plague vapors and flag the cleanest line. It costs us a few breaths now and may spare us fever—or worse—later.” She produces her journal and a vial of rue-infused ink, already kneeling to begin the ritual unless anyone objects.

Once finished she observes the room and describes the safest route to the others. 

Standing well back from the fumes and covering her nose and mouth, Val patiently waits for the team to move on.

"We have already been through it, no need to spend 10 minutes before continuing"

((This is correct, right? We already walked through this room?))

Sarris nods to Gorin, "We did a VERY quick lookabout on our first trip down here.  With the stink and cloying air, we did not waste time slow probe-ing walls.   And the bit to the north takes a turn we decided to skip for another time.   Looks like that time is now."

Sarris checks -     Perception:  18         Survival:  21

Sarris will retrace their path until the group is at the stairs to the entrance of the stinky zone.   "Do we go and explore the additional area north and east or do we loop back down to the know doorway?"

"You just go on and decide that I would say Sarris, it is your privilege as point man, just make the decision now." Val calls out from the back.

There seems to be no change in the room. It still has a certain smell to it and nothing else.

"Yes, we'll follow you," Arkon encourages Sarris, hardly remembering the layout himself anyway.

Marasatra closes the rue-ink vial with a resigned click. “Very well—expedition over caution today.” She rises, dusts her knees, and gives Sarris a small forward sweep of her staff. “Point man’s prerogative; take us on.” Pulling her a damp cloth back over mouth and nose, she slips into formation behind Arkon, eyes narrowed against the reeking gloom as they advance.

Sarris nods and steps forward heading up, around, and down to the southeastern corner... to what seems to be another hallway to the east.

Stealth: 22

Sarris takes it slow and cautious as he leads the group through the murky waters and cloying air of this area;  trying to keep slogging and sloshing to a minimum. 

(( remember, water slogging is half movement... so it is a long, slow trip ))

In what seems an eternity but was only a handful of minutes, the group arrives down at the area to the southeastern wall.

Zim perception check 10 

Again the invisible imp would scout ahead of the team of deputees.

Stealth: 22
Perception: 4 

Gorin stays at the back as was the usual when walking in file.

Arkon does his best to pay attention for any unwanted surprises.

Perception: 18

Updated Map -

(Sorry, Imgur had a data breach so was recovering/changing PWs.)

Mal would fly down the corridor to check the corners for anything hidden, letting Sarris decide which of the four doors to try first in their search for cultists.
Since they had not seen any traces of the dragon cultists down here yet, Valeria hoped they would have cleaned up some for them ahead.

Sarris passes back a whisper of what is ahead - the doors and odd alcoves.  "We may wish to check for traps at those alcoves - just in case.  I would hate to have something suddenly at our backs as something springs from the front in these narrow hallways."

Perception: 11

Sarris will slowly move forward toward the first alcove.

Marasatra edges up behind Sarris and taps his elbow. “These wall recesses are perfect pockets for glyphwork,” she murmurs through her cloth mask. “Give me ten minutes to kindle detect magic and I keep within fifteen feet of you—anything arcane will flare before we blunder into it.” She slips past Val and Gorin to settle just behind the ranger, already uncorking her silver-ink vial and drawing a fingertip circle on the damp stone.

“If anyone objects to the brief pause, speak now; otherwise hold position while I finish the sigil. We’ll trade the time for fewer surprises.”

(Perception: 6)

Valeria simply nods and waits for the more thorough investigation. She felt it would be strange for the cultists to place random traps inside their supposedly secret lair but there was a lot about this place she didn't quite understand, and there were no reason to unnecessarily walk into more traps and ambushes.

(You can assume Mal will open any doors that need opening.)