Quote from Cyb3rM1nd >>

OOC:

Tracking if something has been through an area is more of a Wisdom (Survival) check. History is typically recalling information learned before. Unless DM wants to rule differently. 

Blood-Hunter: Grim Psychometry

When you reach 9th level, you have a supernatural talent for discerning the history surrounding mysterious objects or places touched by evil. When making an Intelligence (History) check to recall information about a darker past surrounding an object you are touching, or a location you are present in, you have advantage on the roll. The information gleaned often leans towards the more sinister influences of the past, and sometimes conveys visions of things previously unknown to the character on higher rolls.

(I've used this Critical Role feature before, it's legal)

OOC

Yeah, basically if you make a History check and it concerns something dark/evil you get advantage. That's for history checks. Your character is determining if the prey passed through, which is a Survival check - you're checking for signs and tracks a creature has passed through not delving into the mysterious historic lore of a dark and evil object/location.

Again, DM's call. I point it out to advise and ensure the right check is used, in case. But, I'm just a player and trying to be helpful. I don't particularly care either way, and it was a good roll so if the DM's agrees, all the better. ¯\_(ツ)_/¯

(@Cyb3rM1nd  I won't be surprised if Maerwyn finds nothing with a natural 20, since there's a possibility that the Mindflayers never passed through it. The rule seems weak enough to be exploited, nobody will deny the fact. I always appreciate your help and concern.)

Quote from InkedBee >>

(@Cyb3rM1nd  I won't be surprised if Maerwyn finds nothing with a natural 20, since there's a possibility that the Mindflayers never passed through it. The rule seems weak enough to be exploited, nobody will deny the fact. I always appreciate your help and concern.)

 *I think that would be survival check.*

Quote from InkedBee >>

Maerwyn will try to feel the interior of the hallway using the palms of her hands, she trails the walls carefully with finger-tips, sometimes pausing frequently to kneel down to touch the ground. She's been trying to find out if the Mindflayers have passed through this passage, or whether they have sent more of their minions through this path to do their dirty business or not.

Intelligence (History): 21 (rolled in gamelog with advantage from Grim Psychometry class feature)

Grim Psychometry: When making an Intelligence (History) check to recall information about a darker past surrounding an object you are touching, or a location you are present in, you have advantage on the roll.

 (@Orange20 @Cyb3rm1nd Let's see if this works.)

Grom glared at the space where the wall had been as though its disappearance offended him. In a way, it did. "Magron, did your enhanced sight show an illusion here or did this wall seem real? If it's the latter... our minds may already be compromised. Obviously, walls don't just disappear."

Finding nothing of any importance, Maerwyn stops examining the walls and stands beside Grom to face Magron. She will try to join the conversation with a muted voice:

"I was wondering if it had been a consecutive entrapment of illusions to drive us insane. Have you seen the third Intellect Devourer trying to converse with Dusk? I swear that I never heard these creatures speak before.....they only communicate through telepathy!"

Honestly, she's been surprised to find the Intellect Devourer showing peculiar behaviors, as well as her own foolish attempts to recall an unknown past made her flabbergasted.

Quote from InkedBee >>

Quote from InkedBee >>

Maerwyn will try to feel the interior of the hallway using the palms of her hands, she trails the walls carefully with finger-tips, sometimes pausing frequently to kneel down to touch the ground. She's been trying to find out if the Mindflayers have passed through this passage, or whether they have sent more of their minions through this path to do their dirty business or not.

Intelligence (History): 21 (rolled in gamelog with advantage from Grim Psychometry class feature)

Grim Psychometry: When making an Intelligence (History) check to recall information about a darker past surrounding an object you are touching, or a location you are present in, you have advantage on the roll.

 (@Orange20 @Cyb3rm1nd Let's see if this works.)

 *Success. They did pass through.*

"As I said, arcane lore is not my forte. I would not think it was illusions though, but rather enchantment. As in, they're affecting our minds directly, without messing about with images and sounds. The effect can be similar, I guess, from the perspective of the one suffering it. I know such a spell... I could protect two of us from such influences, but not all four."

"I do not need such protection, Grom," Dusk said, "but thank you. I have protected myself before encountering any of these creatures, I cannot be charmed, my thoughts cannot be read, and I'm immune to divination magic as well as psychic attacks. Whatever caused the wall to disappear, it was not a direct effect in our minds. Let's just get moving."

Dusk continues down the path.

"As I didn't notice anything, it must have been an enchantment indeed. I do have access to some extra protection against spells that provide these type of sufferings, but no immunities unfortunately." 

"I disagree. If it was enchantment we're talking a level of ability beyond what any mortal creature in known existence can achieve, given my own protection against such can foil even wishes. Your premises are based on 'walls don't just disappear', when I know of 4 different spells all capable of achieving this, one of which I can even do myself. There are also creatures capable of altering terrain: including walls. An intellect devourer can take over a host creature, including their skills, abilities and memory. If an intellect devourer took over a mage, they can cast spells. If they took over a creature able to alter terrain, they could do that to. It would also be very unreasonable to assume a Mindflayer could not learn magic themselves. The wall could be altered, or it could be an illusion giving way once your true sight foiled it. There are many possibilities  "

"So," he continued, "Should we assume these are beings transcending all known magic - with levels of enchantment until now known only by Gods, meaning we are royally ****ed, have no chance of any success and should wait for these things to easily take over the world. Or should we think of them as mindflayers and not get so worked up over a parlour trick?" Dusk demonstrates casting Passwall with his staff to remove a large section of wall creating an instant 20 ft tunnel in a single moment.

He sighs and continues down the path they believe the Illithids went.

Maerwyn will wave her hand in dismissal, then continue to speak to the Cleric:

"I think he's just trying to be polite by refusing your aid. No matter what spell he had cast upon himself, additional protection will keep him out of harm's way".

The woman stares at the Tabaxi Male with concern and taps her heel on the ground while seemingly absorbed in deep thought. With a quick snap of her fingers she will make a clicking sound to cast Prestidigitation. She will draw a horizontal line on the surface of the wall supplementing it with two other vertical lines to mark it as the Illithids' route of moving around, the neon sign will keep glowing in the dark for about an hour.

As a bonus action she'll try to grab on the sleeves of the retreating figure, grappling him back towards the Cleric with a soft pull. 

"Is this statue a miniature version of our mate 'Dusk'? I think this little guy needs some protection."

The grim lady will poke at the statuette to compliment it's adorable feature, when indicating Grom to start the enchantment. 

Athletics 25

Acrobatics Check to escape the grapple. 13

Dusk snarls at the elf's inconsiderate actions. Raising a hand as a gesture to prevent Wispy attacking her, he turns to her barely containing his seething rage. "I am protected with the greatest mind-defending magic ever known. That is why I declined Grom's offer. And regardless of why, if I decline, I decline. You hold no authority over me and the next time you lay a hand on me in such a way, I will do everything in my considerable power to ensure you never get to do so again."

After speaking he reaches under his collar to one of several necklaces, bringing out one that features a pendant-like gem with what seems like clear liquid inside. He mutters words under his snarls as black smoke surrounds his hand and gem. The bat flying around disappearing in a puff of green light. He then throws the smoke to the ground next to Maerwyn, it drops like it is heavy, but begins to rise into a black, smoky, humanoid shape with a large menacing sharp-toothed maw and large slit eyes both emanating a deep swirling red light. Its hands extend as large claws tinged with ice. He had cast, Summon Shadowspawn (Fury). 

With the Tabaxi she has grabbed, the elemental and this shadow creature at her sides, Maerwyn is flanked and surrounded.

"Unhand me." he says with a glare full of disgust. 

"Wasn't the plan to work together? Of we are going to fight each other we wont stand a change against those mindflayers... So how about Maerwyn you let go of Dusk, and we move on.

What protection do you mean Grom?"

The Blood-Hunter has been faced with such kind of hostility many times before, thus she had advantage against being frightened. After all, these hunters are considered as the hardened souls to challenge fierce fiends, or unbeatable undead creatures. 

"You're dismissed! Do tell your summoned companions to get off my toes."

She lets out a shrieking scream when few locks of dark hair falls over her face to accentuate her feminine features, she seems few years younger than her real age. She's completely frustrated with the situation at hand, moreover the hulking man has irritated her to a great extent. Next time, she'll be careful not to step on other people's tails, especially maintaining safe distance from furry claws.

"Enough, both of you! You're acting like children. Dusk, you are the expert on the arcane here, so I will defer to you, but don't fall into the trap of assuming that you know all there is about it. That sort of arrogance will get us killed. Spells are invented all the time, and besides these aberrations have powers that are poorly understood. Not so?

And Maerwyn, please refrain from touching Dusk without his permission, it's a violation of his personal space. "

Dusk, for a third time, tries to proceed down the passage. His elemental and shadowspawn in tow.

At this stage Dusk was beginning to wonder what he is doing here. He doesn't owe this town anything. There are other ways to get gold. These people... Two stand around overreacting to a wall disappearing, his words to encourage them to press on falling on deaf ears. Then the other invades his personal space to grab him and pull him to have others cast unknown spells upon him, by complete strangers, even after he declined? And then one calls him a child for being angry at said violation? Really? What is with these people? This. This is why he prefers being alone using only conjurations. People are so... So... Whatever.

Oh, but mindflayers left unchecked would be a problem. Selfish though he was, lazy as he might be, he is not so evil to resign innocents to such an abhorrent fate. He will continue to try to get on with these people and their ... Quirks. 

Maerwyn stands still for awhile folding her hands before her torso, she's been reconsidering the cause of the sudden hostile reaction of the Tabaxi male. It could have been the invasion of his personal space that had influenced him to see red, or it might be her comment about the spellcasting component that hit his pride. She nods her heads side-by-side to take a mental note, then pulls out the vial of Potion of Psychic Resistance gulping down the liquid all at once then striding towards the end of the passage. To her, the glowing rats outside seemed like better companions than the bloke with claws, they haven't shown any dismay even if they're literally stepped on.

((Twinned Spell protection from evil and good))

Grom turns away from the mage's retreating back and toward the others. "It's a simple spell which normally protects against evil and good outsiders. It will prevent your minds from being taken over but I can only protect two. Give me your hands." Clasping them briefly, he speaks the words and performs the gestures. "It will last for ten minutes, tops, but I can recast it. We had best follow him. We should not split up here."