The creature, its skin peeled away, leaps at Peri:

Bite Attack: 14  Hit: 14 piercing damage.
Claws Attack:25  Hit: 9  slashing damage (and a DC 12 CON save)

...A saving throw for Peri, and everyone may act...

Peri:

Peri, about to pursue, is surprised when the thing comes screeching back into the shop. He twists out of the way of its fetid teeth, but its claws rake down one arm. CON save: 13

Also Peri:

Peri has no idea how much they've hurt this thing, with the tiefling suit falling to pieces all around it. It's unlikely the thing will answer any question -- What can we threaten it with, being flayed alive? -- but he tries to disable it anyway. He brings the spear shaft up into its jaw twice:
Spear Attack #1: 16 for 12 nonlethal damage
Spear Attack #1: 23 for 8 nonlethal damage

The astral arms, acting almost of their own volition, rear up to the ceiling and then crash down on its head like an ethereal piledriver.
BA: 16 for 5 nonlethal damage

Gerrard:

Stepping up next to Peri, Gerrard focuses on the horrific creature, then suddenly switches places with the halfling, even though they both remain engaged with the creature!  "This abomination seems to have a taste for you, Master Fenwader," he quips, his blades weaving a defensive dance between the halfling and the foe before darting in and trying to further subdue their enemy.

Bait and Switch Maneuver adds 6 to Peri's  AC until the end of Gerrard's next turn (Combat Superiority, no action)

Elegant Rapier Attack:  Attack: 28 Damage: 15

Elegant Rapier Attack:  Attack: 11 Damage: 9

Main Gauche Attack:  Attack: 20 Damage: 7

Peri and Gerrard team up, and in an impressive barrage of weaponry, finally take down this charging horror. Rudely ignoring the party's attempts to subdue it nonlethally, the monster immolates violently. Flaming bits of rotten tiefling flesh are sprayed throughout the vestibule, lighting some of the scattered papers aflame. Combat is over.

Gerrard:

Leaping over to the papers, Gerrard tries to stop them from burning as best he can, saying, “The answers we seek may be here.”

Peri:

Peri also begins stomping out fires. "I was a bit hasty earlier; I thought with Xondros taken out the henchmen would be lightweights. But now can you please try to keep her alive? We need answers, and she needs a less noble way out than a clean sword to the heart. If anyone deserves to dance on a rope..."

Kei 

With a sigh Kei obliges. "Can't believe you're making me do this" he grumbles. As the others try and stamp out the flames he looks at the hopefully lifeless body of Xondros  and whispers a Healing Word. He waits to see what happens to the inert tiefling, ready to launch a more destructive boit of magic her way if need be.

5

Gerrard scrambles to put out the flames. DEX check: 21 

...and just manages to smother the flames before one errant fire alights a bin of oil flasks. The flames are out. He begins to examine the papers. They seem to be mainly ledgers full of fish tallies - varieties, amounts, costs, dates, etc. - although some of longer passages are in a language you cannot read.

Meanwhile, Kei tries to resuscitate Xondros. She still breathes, and lurches back into consciousness rather abruptly upon receiving Kei's magic. Inhaling sharply, she lunges for something in her pocket.

Roll initiative again! (Peri and Kei can roll normally. Gerrard may also, but he is occupied this turn in the other room, with flames.)
Xondros: 3

 

Peri:

((Initiative: 15 -- Since it can't be less than 5, I'll post with the assumption Peri gets the drop on Xondros))

Peri hears Xondros gasp awake. "You were supposed to keep her alive, not wake her up!" His astral arms fly out and wrap themselves around her wrists, trying to pin her arms to the floor away from her body. ((Grapple check: 6)) He strides over, leans down, and punches her behind the ear.
Unarmed strike: 23 for 6 nonlethal damage

((BA 2nd Unarmed strike if his first misses: 26 for 8 nonlethal damage))

Gerrard:

Occupied with extinguishing the flames, Gerrard responds slowly to the awakening foe.

Initiative:  18

Kei 

Initiative 22 

(Taking into account Peri's actions and Kei's inability to roll less than 5 also)

The tiefling awakens with more zest than he had hoped. Peri's quick actions though seem to soon subdue Xondros. "Didn't even expect her to live if I'm honest." He's so blunt about it, Dwal would've been proud.

Gerrard:

Ready to leap into action, Gerrard is relieved when Xondros falls back into unconsciousness.  As he shuffles and sorts the papers into something resembling a pile now that the fire is out, he says, "I thought I saw her reach for something, maybe in a vest or pocket.  Given that she has access to many powerful items and just used one to breathe flame on us, perhaps searching her person and removing any such items of power would be prudent."

Holding up one of the papers with what he assumes is either her native tongue or a fiendish script, Gerrard says, "Can anyone read this?"

Peri:

Peri quickly trusses Xondros's hands behind her back, then thoroughly searches her, using his Eldritch Sight in case there are any innocuous-looking items that are enchanted. (Investigation 4, and pocketing anything magical to take to Dwal for identification) He looks over the papers but none of it is legible to him; the writing makes him slightly queasy, though that could all be in his head. "Xondros always had magical goods for sale; said she had the good stuff locked away from us riffraff. They've gotta be around here somewhere." He scans the room, again looking through his enhanced eyes to spot any magical auras. (Perception 19)

Unconcious again, Xondros is quickly secured. In her pocket she carries a pair of vials of potions with differing magical signatures - one small vial containing something metallic, like a dull mercury; the other a yellow liquid swirled with black. The thin black gloves she wears also carry a magical signature. These appear to be the only magical items detectable here - nothing else besides what she was carrying.

There are more papers in the office with a similar script to those that Gerrard found. Peri cannot read the language. Nor can Kei.

Peri:

Peri pockets the potions and struggles removing her gloves. Never tried to take someone else's gloves off... He looks around in disgust. "She said there was powerful stuff. Where is it?!" Frustrated at having to wait for her to wake up again -- And whose fault is that? -- he considers ripping out the walls and floors. He pitches the idea to his companions. "Maybe we should get that dwarf down here to help. He's handy with tools. And we need him to tell us what we find anyway."

Gerrard:

”Good, she is disarmed now, I hope.  The fire is out too.  Should I go fetch the Guard now?  Captain Farbern needs to know what happened here, and perhaps he can question her properly,” replies Gerrard, looking towards the main door to see if it is still open from when the skeletal horror fled briefly.

Kei 

The audible sigh would wake a sleeping dwarf. "Always with the authorities. You'd think you would've learnt by now" he grumbles as he begins to search the entire place beginning with the back room. "Hmmm, perhaps some extra help wouldn't go astray".

Investigation 6 plus 4 Guidance 

As he searches he continues to talk to Gerrard. "I know you want to do good and all, but can you imagine the questions and judgement we'll receive. And we've got that meeting to get to. I can make one of the bodies disappear for a while if that helps. Make it look like that ghoul thing attacked Xondros and they killed each other." He pauses while he thinks through his plan. "Means we'd have to dispatch her ourselves though, which I think is justified. But hey, go see what that fool guard has to say."

There is little else apparent - besides singed papers and ledgers, a few books and knickknacks, furniture, oil, and household/office miscellany, there's not much to note. Peering into the side rooms reveals a couple of small bedrooms and living quarters, a larger supply room and workshop for barrelling and crating fish, and a small room, smelling of death and burnt metal, with some kind of arcane circle hastily drawn onto the floor with chalk.

The front door is wide open, with two wide-eyed old drunken men staring in. Xondros is tied up and unconscious; Kosrus is quite dead. The thing that immolated is nothing but thin ash.

Peri:

"Oi! You two! Go and fetch Farbern!" And he slams the door shut. "Too late to cover it up now, though I would have been inclined to do just that too. Still, I'm not turnin' Xondros over to anyone until she answers some questions." Peri snorts in disbelieving amusement. "You really think Farbern will 'question her properly?'  The guy who never showed up to Armand's murder? Whos never even looked into the skiff fulla contraband that just went missin'? Do you remember the night we got back with Aubrek's box, and we had to step over a dead body in the street on the way there? Wanna bet that mystery's been solved by the brilliant Saltmarsh Guard?"

Peri shakes his head. "Kei's right -- if you want to do any good for the people around here, you're gonna have to unlearn some of those noble instincts. I'm sure, if it was someone in your social circle who'd been killed, there woulda been an epic manhunt. But that ain't most people's experience. I used to think Farbern was in on the crooked dealin' with the smugglers and all, but I think maybe he's just got his hands full with the jackalweres, ghouls, gnolls, and Yondalla alone knows what else wantin' to eat all the good townsfolk. And no guard worth his rum ration would stay in this sinkhole, so he's stuck with a buncha Butters. No, WE will take care of OUR business. Farbern can hang Xondros when we turn her over."