You have heard of such creatures but perhaps had never seen one before.  The creature chained to the statue is a Mind Flayer.   Someone has amputated its face-tentacles and as you look at it it shies away from you.  It looks to be in a very weakened state.

Chill meanwhile inspects the duergar encased in the cruel-looking exoskeletal construct but he is unsure what it really is.

Chill, roll investigation.

"That is a mind flayer, a very vicious creature from the Underdark! Even without their tentacles they could still be dangerous, do not get too close." says Krom as soon as he recalls the stories about such creatures.

The dwarf points at the side door on his right "Vellyne may be in one of those side doors, let's check them before opening the double doors." He then adds "Chill, the side doors may be locked or trapped, could you take a look?"

Chill Investigation 28

Kazri has heard of legends regarding Mind Flayers, but never seen one herself. She keeps her distance. "Do you have a name?" She ask inquisitively.

"I've heard few tales of such creatures. But from what little even I knew..." Rhogar lets things trail off from there as he'd begun circling about the imprisoned creature while wearing a look between pity and.. respectful wariness. He would take Krom's advice to heart however and keep from getting within 5ft of it if at all possible. Eventually he turns to Dreck and asks, "What's through the double doors? More... macabre kept prisoners?"

Kazri questions the mind flayer that surprisingly does answer you. Kazri hears the answers in her head as the creature speaks telepathically to her

Kazri only hears the answer:

Dreck answers Rhogar "The priest lives there.  He is not on our side."

Meanwhile Chill is still in the previous room studying the construct.  He comes to the realization that the creature is not just encased as a statue but is in fact some sort construct.  

It suddenly moves and attacks Chill

Initiative Construct 14 Chill 16

Having once again lost track of Chill, if though this time with his focus on Dreck, and without immediately knowing of the creature's communication with Kazri, Rhogar carries on by saying, "Mn. I cannot say I'm particularly keen on attacking a member of a clergy -- any clergy. But, if reaching the prisoner area or the torture chamber means cutting through their domiciles, then... I'm afraid we must do what we must." He side-eyes Krom with a crooked grin. "Not that such is much concern for some of us anyways.. Hmph... So pretell, Dreck. How might we best reach it from here?"

Krom, placing an hand on the head of his warhammer, grins back at Rhogar. "Indeed Rhogar, as we are on a tight schedule, we must do what we must." 
The dwarf shifts his focus on the duergar and pointing at both side doors asks "Dreck, what's inside those rooms?"

"Where is Chill?" asks Kroms as his question to the tabaxi goes unanswered.

Chill reacts quickly, his rapier already at the ready.  As a BA he steadies himself (Steady Aim) and drives the point of his rapier into the construct.

Attack: 18 Damage: 25

He'll react with Uncanny Dodge if he is hit

I'll use Piercer: Reroll Damage to reroll the 1 6

And just to speed things up here is next turns attack roll as well if needed.

Same BA and action and reaction.

Attack: 26 Damage: 29

Kazri informs Rhogar about the temple's priest, and that his name is Klondorn. She was about to ask more questions to F'yorl, but Krom grabbed her attention. She scans the room quickly for Chill. Without finding him, she goes to the room from where they came from. If she's able to engage the construct, she will attack it.

Dragon Slayer Attack1: 23 Damage: 7

Dragon Slayer Attack2: 19 Damage: 12

(BA) Kazri will try to shove (5ft) the construct away from Chill: Athletics: 25

(@Chill. Let me know if it’s ok to get Chill out of harm’s way. I can cancel the shove if you prefer to stay melee range.)

Attack: 18 Damage: 6

Attack: 12 Damage: 9

Chill is alert and when the construct suddenly attacks he is ready.  He drives his rapier into the monster who claws at him but Chill is able to dodge out of the way and is barely struck.  Chill strikes again and the construct falls dead.

Kazri rushes into the room to see where Chill is only to find him standing over the fallen construct.

Chill stood over the construct as Kazri entered the room. "Uh, yeah, so it wasn't just a statue and it attacked.  But I'm OK.  Let's get back with the others and see what's going on." he says casually sheathing his rapier and moving on with Kazri to catch back up.

Chill and Kazri catch up to the rest as Dreck is answering Rhogar's question.

"Those chambers are east of here, though you would have to go through the forge to get there. It would be tough to be stealthy and sneak past but there are guards on our side down here.  Perhaps it is time to try and overthrow Xaradok and rally our people to our side." 

Rhogar grimaces. "Difficult for all of us, but... not some of us." He says looking to Chill. Gorrah, however, takes that as her cue to peek her head out and nip at the dragonborn's jaw elicting a pained ground. "What? I did say some of us you coo-coo little dragon." He admonishes, earning himself a close nip at his face again.

"Ugh. In any event, is there no way you can convince the guards to provide a... I don't know. A distraction of some kind to allow such passing to the east? For as unlikely as it is, the prisoner we're after would be a boon to the cause... if she yet lives." He asks of Dreck.

"Here you are Chill." nods Krom as Kazri and the Tabaxi rejoin the group.
"I agree with Rhogar. The person that we seek, if she still lives, would be a powerful ally against the Warlord." says the dwarf to Dreck as Rhogar finishes to speak.
As Krom speaks he keeps within his sight the mind flayer.

Seeing Chill is safe, Kazri returns to the Deep Duerra's chamber. "I agree with my friends, we should try to make the rescue of Ms. Harpell a higher priority, if possible." She turns to the Mind Flayer. "I do not make any promises Mr. F’yorl, but I do need to ask. Do you wish to return to your people?" She then asks Dreck. "What is the story for this one? Do you know?" She tries to determine how he or his people feel about this particular prisoner.