Sekkar Nature check 26 (+6 more if we are in the Underdark still) (Brain grandmother's name on top of that SIN?)

Both Sekkar and Derendil stopped abruptly at the sight. Derentil just growled - lower menacing warning growl of a predator, his eyes flashed with angry terror. Sekkar did not growl but his hissing was as threatening. "Illithids! We are in the lair of a mind flayer." He did not add more - anyone who spent any amount of time in the Underdark was expected to know the word (and hundreds of horror stories attached to it) but for Sekkar it was much more than just stories. "We need to leave now, even purple worms are better. If not - fight to the death, do not let them get you alive." He hissed some more torn between two wishes - to destroy everything and everyone here or to save the group by running as far and fast as they could.

Pax glances over at Sekkar, "If I wasn't staring at a giant moving brain thing, I'd think you were talkin about childhood boogymen that eat brains outta people's heads, but...I'm willing to give you the benefit of the doubt on this one."  She pulls the tentacle rod out from her belt loop.  "We're here, let's kill bad things. They're not going to let us be for a day while the helm recharges."

Prior to them leaving the room Kaylyn has Pensive bring him the musical instrument.  She then considers and has him bring her the parchments with the writings and diagrams.  She then compares them with the writings Kirin has found.

She then casts Comprehend Languages and reads what is said as quick as she can.

"All horrors are real in tunnels." Sekkar licked his lips and summon the blade. "Then we kill it. All of it. If it moves - it should die here. If it does not move - it should die too." He looked at barrier and around it more attentively.

Rhayna looks at the parchments as Pensive brings them to Kaylyn. The 'writing' appears at casual glance to look like nothing more than series of parallel lines, but Rhayna recognises the script immediately as 'Qualith', the written language of the illithids, which they read by scanning the lines with their four facial tentacles to receive the psionic message they convey. There were several documents in Candlekeep, but none could be read without the benefit of magic... Which Kaylyn promptly casts...

The documents are the results of some research conducted by a mind flayer on kuo-toa brains. It seems they are attempting to find a cure for a terminal disease being suffered by their elder brain, and are exhausting every avenue of inquiry. This particular page examines the ability of the kuo-toa to perceive the ethereal, and discusses whether feeding specific lobes of a kuo-toa brain to the elder brain might allow it to partially project its consciousness into the ethereal and slow its decay.

Sekkar correctly identifies the horror in the room beyond as an Elder Brain and recalls perfectly all the relevant lore and strategic information that he has learned about them, promising to convey as much as he can to the others. But there are different specialties of knowledge, and Kirin observes something about the elder brain that Sekkar does not. It is dead. Or rather it was. It is in fact undead. The black lesions that spot its surface are telltale signs of advanced necrosis, and would normally be fatal to even a creature such as this, but the unmistakable signs of motion indicate that the brain still exhibits animated movement. Kirin's opinion is that in such a state the elder brain would still retain many of its normal functions, but would lack many of its psychic powers.

((OOC: Two awesome rolls, which deserve extra information. Everyone is free to examine the monster's stat block, but note that this Elder Brain is an undead rather than an aberration, and lacks the Creature Sense, Telepathic Hub, Psychic Link, and Sense Thoughts abilities, as well as lacking the Legendary Actions Break Concentration, Psychic Pulse, and Sever Psychic Link. Of course there might be some other changes, but even Kirin and Sekkar don't know everything, right?))

Pax tests the limits of the door, but neither the chalk nor the spectral hand or anything else seems to be able to penetrate the barrier. Pax's guess is that even magical effects like teleporting will probably also be denied. However, the hum coming from the barrier suggests it is being powered by something, so perhaps disabling the source of the power might be enough to lower the barrier. It also seems there is another entrance to the room further south on the same wall.

Of course, Sekkar shared all he knew about the ting, with some one-word incomprehensible comments from Derendil, who overcame his (quite justified) initial overwhelming angry panic. The lizardman was listening too, but Kirin's conclusions did not calm his worries a bit. "Now it is also undead? Great!" Though when initial agitation passed he begun to think more rationally and see some reason in Kirin's words. "It did not take our brains. Yet." Sekkar looked suspiciously at everyone. "But kuo-toa acted like usual thralls. Either illithids are around too - they have to be - or it works somehow else." He shivered and repeated. "Great." "Let's kill it." He tried the wall around the barrier with the shining blade of Dawnbringer - in several places, to see if the "door frame" could be cut. And then walked to the sought entrance.

Rhayna looks at the Elder Brain and tries to determine how long has it been “undead”. (Medicine: 13)

Pax listens to all this with a dark furrow beneath her helm. She glances at the creature then back at her allies. She's in agreement with Sekkar. There are other things around here besides this one brain. 

With the only obvious way to get around to the thing being the long hallway they haven't been down, Pax waits for a few moments to see the result of Sekkar trying to cut through the wall itself. Surely a giant brain creature wouldn't create a stronghold powered by some mystical energy that can create magical impervious doors, but not have the walls equally protected.  But....who knows.  

Assuming the predictable thing happens and the walls are impervious, she turns with Sekkar and marches down their long hallway, their only other option, to try and find either the power source or the other way around. Her weapon is grasped in her hand, ready. 

(Hey, it works with lightsabers. Isn't that what Dawnbringer is?)

Despite Sekkar's best efforts, Dawnbringer makes no impact on the walls around the barrier. Short of painstakingly mining around the barrier, there doesn't appear to be any simple way through or around it, so the decision is made to try an alternative route.

Heading back into the common room, the group moves east along the remaining corridor. The background humming/buzzing sound increases as the corner draws near, accompanied by a faint metallic tapping noise. Pax is the first to reach the corner, and peeks around briefly before advancing... then snaps back with a warning look to the others when she sees what's around the corner...

Six cylindrical glass pods, reinforced with metal bands and filled with some sort of glowing liquid line the western side of this elongated room. Three of the pods are opaque. The fourth is empty. The fifth contains a kuo-toa but it has a grotesque elongated head with enormous eyes, and stunted limbs. The sixth pod contains another kuo-toa with part of its brain exposed through its skull and two extra arms stitched to its torso. A single mind flayer appears engrossed in studying the fifth pod at the far end of the room, tapping on the glass. The buzzing sound is quite loud enough now to drown out normal conversation.

Kirin taps Sekkar on the shoulder to get his attention before pointing at the mind flayer, making a gesture across his throat then giving a thumbs up and down then up and down repeatedly while his face is state of confusion. 

(Is there any “control panels” in this room?)

(I was sure it is! Find one difference aside from talking!)

Neither Sekkar nor Derendil needed any encouragement to attack a mind flayer and the ranger was pretty serious about "kill anything that moves" here. That one was moving and on the way to their goal, it had to die. The lights were masking Dawnbringer's light and the bussing muffled footsteps and the voices. "Let me strike him first, then keep your distance - the monster can and will eat your brain while you are still breathing." The reminder was probably unnecessary but Sekkar wanted to emphasize the danger. "We need to kill it very fast." Sekkar lowered the hood of his cloak and moved forward as softly as he could. (Shiny blade can be hidden under the cloak)

Initiative: Sekkar 7 Derendil 7

Stealth: 24

If surprise round works: BA Zephyr Strike

Ambusher attack: Attack: 22 Damage: 14 + 3

Attack 1: 25 Damage: 14 + 1 Sneak

Attack 2: 26 Damage: 14 + 4 Zephir

Move past the MF, right behind next exit, hoping to keep MF's attention on himself.

Pax prepares herself, standing still as she can, the darkness swirling around her...emanating cold energy. The tentacle rod is ready, and she's focused on keeping her counter spelling ready, in case that works on these freaky weird mind eaters. She otherwise waits for Sekkar's sudden attack before executing her plan of rushing around the corner to attack.

Kaylyn, waiting for Sekkar to attack, has no desire to do anything but slay the creature as fast as possible.  After Sekkar engages the creature she summons her eldritch energy and two beams of crackling energy fly towards the mind flayer.

Attack: 23 Damage: 14

Attack: 12 Damage: 6

Kirin was not expected that much murderous vigor and that aggressiively about it. He just takes a step back keep his staff in between him and the creature while he watches I guess (Dodge action basically)

Quote from BlueBayou >>

 Initiative: Sekkar 16
Stealth: 31
If surprise round works: BA Zephyr Strike
Move past the MF, right behind next exit, hoping to keep MF's attention on himself.

I must admit, I read that 'MF' abbreviation as something different the first time, until I realised it meant Mind Flayer.

Another nat20 on the Stealth roll! Surprise Round does indeed work. 

Since everyone seems happy to let Sekkar go first, I'll say everyone roll initiative and if your roll is higher than Sekkar's 16, then you can declare a Ready action for the surprise round, so you still potentially get to take an action after Sekkar.

Mind Flayer Initiative: 4 (for the next non-surprise round)

Quote from BlueBayou >>

 

Ambusher attack: Attack: 18 Damage: 17 + 1
Attack 1: 27 Damage: 11 + 4 Sneak
Attack 2: 15 Damage: 16 + 1 Zephir

 Just being nit-picky here, but I notice you have advantage on all three attacks. I can allow advantage for the first attack on the basis on being unseen. Another attack gets advantage from Zephyr Strike. But either the second or third will have to be normal (and will miss on the basis of taking the first of the two rolls). The Sneak/Zephyr damage can still be applied to the attack that hits. Correct me if I'm wrong, but I'll assume that the first and third attacks are the ones that hit, along with the Dread Ambusher, Sneak and Zephyr damage, for a total of 39 damage.

Pax Initiative : 20

Seeing Sekkar's blazingly bright sword light up the hallway as the lizard slashes into the Mind Flayer, Pax spins around the corner and starts walking calmly towards the creature.  She focus' her animosity at it, and motes of blackness seem to sparkle around it.  (BA: Casts Hex on the creature, targeting DEX ability checks.)  Then she lashes forward with the tentacle rod. 

Attack: 25 Damage: 7 (combination of bludgeoning and necrotic)

Attack: 17 Damage: 6 (combination of bludgeoning and necrotic)

Attack: 22 Damage: 7 (combination of bludgeoning and necrotic)

If all 3 hit:

 Still moving forward, she aims to end standing right next to the evil creature. 

(Rhayna: sorry, forgot to reply. Checking for a control panel will have to wait until you enter the room. And then it there is one, it will require an Investigation check to determine what it is designed for.)

Quote from ZorgAlmighty >>

(Rhayna: sorry, forgot to reply. Checking for a control panel will have to wait until you enter the room. And then it there is one, it will require an Investigation check to determine what it is designed for.)

 
(I just realized that the Stonespeaker Crystal gives advantage on Investigation. Rhayna is already proficient in Investigation, does Knowledge of the Ages helps in any way?? :-)