(I am assuming Stool has sprayed everyone, so the conversation is easier to follow.) Beegred: "What is the Society? We haven't seen any demons, but this guy has." (gestures to the new elven mouth)

(Since Tozer/Eldeth made the effort to wake everyone, the creature and/or Stool can facilitate communications, so yes it'll be easier and faster if everyone can participate).

The creature begins to speak telepathically to everyone, "The Society of Brilliance is a tight knit group of erudite individuals among the diverse creature races of the Underdark.  Each of us has cast off the shackles of our individual society and are not beholden to any particular race.  As a group we are only interested in study of knowledge, solving problems that plague all of the races and recruiting future members into the society.  Only the most gifted individuals have the gift needed to join, thus it is in our best interest to maintain healthy populations of all creature races to produce these exceptionally rare individuals.  In other words, our mandate is to study knowledge and maintain 'life' in the Underdark.  We currently number 5 of us: a Derro, a Kuo-Toa, an Orog, a Troglodyte and myself, a Mind Flayer.  You may call me Grazilaxx.

The society are currently out and about in the Underdark because we suspect demons have been set loose, which would threaten every race's way of life.

Your companion appears to be comatose.  If you permit me, I can cast a spell and gain insight into his surface thoughts."

(Eldeth will immediately dislike Grazilaxx because he is a Mind Flayer.)

(Jimjar will pleasantly tolerate Grazilaxx, at least until he can make another wager to cancel his debt.)

Beegred Insight check (is this thing on the level, or getting ready for a late night brain snack?): 10 (I trust him)

He does have the snooty attitude of an individual that believes himself to be intellectually superior, thus his claim that he can easily defeat you but hasn't seems honest.  Also keep in mind, an Underdark creature has a good chance of knowing what a Mind Flayer is, but a surface creature would have to be very learned to know what they are.

If you feel your character should and does know what they are, then justify it somehow.  Otherwise roll an INT check  (Nature or History) at disadvantage due to the knowledge being about the underdark.  Beegred, as his favored terrain is the underdark, can roll his INT check (Nature or History) with advantage plus doubled proficiency bonus.

(Unfortunately, no proficiency to be doubled for Nature or History) Beegred roll: 11

During his studies of the Underdark as a ranger, Beegred saw a crude octopus-head drawing and read that "mind flayers are to be feared", but those 6 words are all he can remember on that subject.

Jimjar joins in on the telepathic communication, "Mind Flayer, eh? I've heard tellings of your sort, but in all my time in the Underdark I haven't laid eyes on a one of you until this moment.

Pointing to their newly acquired Elven companion, he continues, "This one over here has seen your demons. Double or nothing, he has the information you're looking for."

Xilyrah tries to recall any lore passed down to her regarding Mind Flayers, but upon hearing the word "Derro" her head snaps up and she asks Grazilaxx, "You mention a Derro. How long has this Derro been in your company?"

Xilyrah Nature Roll (DA): 12

Narstin follows the conversation as closely as he can, but doesn't know what a 'mind flayer' is, though the sound of the name seems rather ominous.

Grazilaxx, still at a distance, still holding his hands out, continues to respond telepathically, "Double or nothing?  For the cost of a coin or two, I accept.  I would know from this one if demons have been set loose upon the Underdark, as well as why and where?  May I approach and delve his thoughts?

I've known 'Y' the derro for many years.  Why do you ask?"

Nature/History check for Tozer: 1 (second roll to reflect disadvantage: 2)

Tozer has no familiarity with the creature that stands before him, nor does he wish to have any. Like Eldeth (who still holds her bow at the ready), he is suspicious and hoping this interaction will end soon. He says nothing, however, to indicate his feelings. 

Xilyrah responds to the Mind Flayer, "Do with that pitiful creature what you will. He came to us talking of a demon attack in Gracklstugh. Concerning the Derro, I was merely curious. We had a traveling companion of that race, but he has since left us on not so friendly terms."

Grazilaxx takes Xilyrah's blazé attitude towards Burfeth as permission to approach.  When he gets closer, you can all clearly see a head resembling an octopus with several tentacles, one of them partially amputated and sporting a gold band.  He wears an impeccably polished breastplate over intricate robes.

Grazilaxx approaches, but only to get within 30 feet of Burfeth.  He pulls out a copper coin, mutters some incantations and motions in the air.  Burfeth makes the slightest movement but remains calm and in his trance.  Grazilaxx mutters, "This one dreams, a trauma of hunger, thirst, abandonment and fear.  I must push deeper to find my answers."

Burfeth WIS saving throw: 13

Burfeth reacts a little more frantically but remains in his trance.  Grazilaxx continues (always telepathically), "Dreams are useful, they can be guided sometimes to reveal information.  This one... this one remembers being with a large caravan of duergar, travelling.  They were attacked.  Many duergar were screaming 'demons', but this one could not see them.  He was told to flee, to return to Gracklstugh.  But he became lost."

Grazilaxx lowers his hands and Burfeth appears calm once more.  "This one has seen something that may be a demon.  I will have to research to identify the creature.  However, he does not contain the information I hoped for, such as why and where.  Snirfneblin, you owe me your last two coins."

Grazilaxx turns his attention to the remainder of the party, "Many of you are not from the Underdark.  Where do you come from, why are you here?"

Quote from Kerrec >>

Grazilaxx ... wears an impeccably polished breastplate over intricate robes.

Grazilaxx turns his attention to the remainder of the party, "Many of you are not from the Underdark.  Where do you come from, why are you here?"

 Beegred uses the corner of a cloth to try to buff out some of the cave slime from his crude improvised breastplate.

"We come from the surface. We're here because Drow came by and forced us to visit their camp east of here."

(Try another Insight, to see whether he likes Drow enough to report to them about meeting our group: 7 Beegred cannot get a handle on what this thing is thinking...)

The completely alien visage of this mind flayer is completely devoid of the usual tells Beegred is used to reading to gauge intent.

Jimjar looks clearly frustrated at the prospect of losing more coin and says nothing more.

Grazilaxx looks from the party to Sarith and back to the party.  "This one drow, who looks too distracted to be a threat, has forced all of you to visit a camp east of here.  And now what are you doing?"

Xilyrah speaks up again, "The elf described what he saw as a towering, big and wet looking monster, like it was flayed.  The ribcage was exposed and a master was in it, but not swallowed.  More like a prison. Have you not come across this demon before in your travels or studies? As my companion stated, we are looking to return to our respective homes after being detained by the Drow at Velkynvelve. And now with the talk of demons, we have even more reason to make haste."

As she speaks, Xilyrah also searches the face of Grazilaxx, attempting to determine his intentions toward the group.

Insight Check: 15

Grazilaxx answers Xilyrah while telepathically communicating to everyone, "Demonology is not my area of study.  No one among the society have had any reason to become experts on the various types of demons that exist in the abyss.  However, all of us will invariably become experts by necessity, which is what usually drives the accumulation of knowledge.  Very few have the leisure time to research a field of study for no other reason than occupying time.

As for your predicament, the drow brought you here, so there are obviously paths back.  Are you on one of these paths?"

Grazilaxx exudes an attitude of intellectual superiority, seeing you as lesser than him.  But he is not treating the interaction with all of you as not worth his time.  In fact, he seems genuinely curious.

"We are headed to Neverlight Grove to return this wee fungus to its home (Xilyrah gestures to Stool) and then to Blingdenstone where we will all decide our individual paths from there. But this elf encountered the demon attack in Gracklstugh, and as that city lies before the others I mentioned, I'm not confident how much farther we can advance."

"From what i could discern from this elf, the attack was not in any city.  Regardless, it is possible to bypass Gracklstugh if you do not wish to pass through it.  The denizens of Blingdenstone will certainly know of a path to the surface, or more specifically to Gauntlgrym and the surface dwarves. 

Unfortunately, none of the society are currently tasked to investigate Neverlight Grove.  However Blurg is on his way to Blingdenstone.  I was on my way to investigate Menzoberranzan, but teleportation is not a precise magic and it spit me out here.  Once I can rest for several hours, I can teleport to Blurg, wherever he may be.  I can bring 8 others with me.  In theory, that should get you past Gracklstugh, hopefully somewhere between Neverlight Grove and Blingdenstone.  If the spell works, and it should as Blurg is a much clearer target for me."