Butching Up Some 5E Mind Flayers

[Sparky McDibben]

Hey guys,

I've got some PCs heading to a mind flayer colony in the next session or two (probably - they could always throw me a curveball). Now, these PCs are absolute monsters, because I've been just screwing around with bonuses and magic items and stuff. Which means that regular mind flayers probably won't work very well - they're going to get creamed.

Besides, I want these mind flayers to be different from regular mind flayers. So I'm looking to butch them up. I'm not looking to see what the following changes do to CR, but rather, does anyone think these will read as unfair to the PCs?

So, changes I'm thinking about making:

Mind flayer changes:

Illithid carapace armour: Thick, bony chitin plates overlapping an illithid's skin. Acts as +2 full plate when bonded to an illithid, raising their AC to 20.

Mind-killer rifles: Psionic rifles that automatically home in on a target's mental energy. These can be fired outside of line of sight as long as the firer is linked to something that does have line of sight on the target (like an intellect devourer). Deal 4d6 + 16 psychic damage, or half on a DC 15 Int save. Range is 300 feet.

Psi-blades: Blades of glowing psionic force, lancing out from the mind flayers gauntlets. Deals 3d6 + 4 force damage, but the mind flayer can make two attacks.

Soulsight helms: Full face-covering helmets that give an illithid truesight out to 300 feet.


Intellect devourer changes:

Death burst: when the intellect devourer hits zero hp, it explodes. 4d6 psychic damage, Int save DC 15 halves

Grapple: the intellect devourer sprouts tentacles and makes an attack. +4 to hit, zero damage, and the target is automatically grappled (escape DC 15).

Teleport: the intellect devourer can teleport itself 50 feet as a bonus action, or teleport itself and a grappled target 30 feet as a bonus action.

Psionic Link: the intellect devourer can psionically link with any mind flayer wearing a soulsight helm within 500 feet of it, allowing the mind flayer to see and hear what it hears.


New monster: the observer

This curious creature resembles a flying squirrel crossed with an octopus. A twisted mind flayer creation, the observer is used to monitor thralls for independent behavior, and make them more susceptible to mind flayer abilities.

Hit points: 5
AC 25
All abilities and saves: +0, no proficiencies.
Speed: fly 50' (hover)

Abilities:
Psionic Link: the observer can psionically link with any mind flayer within 500 feet of it, allowing the mind flayer to see and hear what it hears.

Actions:
Emit Disruptor Field: Anyone within 200 feet of the observer has vulnerability to psychic damage, and disadvantage on Intelligence and Wisdom saving throws.

[Just to Browse]

What level are your PCs?

Mind Flayers: These are pretty strong. I'm looking at at-will 30 damage at long range, +5 AC, and "immunity to sneaking". That said, mind flayers can already punch pretty far above their weight class with int saves and long-duration stuns. I would eyeball these at CR... 10? 9 if they aren't played intelligently? By the same token, if you can deal damage to these flayers, they still fold pretty quick because of their 70 HP.

Intellect Devourers: For usability, I would make the psionic link and the psionic rifle's ranges the same (300 vs 500 seems unimportant, since both are within dimension door range but outside most characters' running distance).

I also recommend removing or weakening Devour Intellect for these guys, because the most effective strategy will actually be a stealth ambush where a half-dozen of them teleport in & spam Devour Intellect on the dumbest-looking party members (grappling isn't great given the teleportation distance is short and their attack bonus is +4). Maybe write these as a cousin of the existing devourers and bump up their attack bonus?

Observer: That action needs a duration. Also it's pretty nasty. These guys have a very sharp strength profile, where their massive range, high AC, flight, and high movement rate make them an unavoidable debuff unless you've got long range saving throws, in which case they fold like paper. I also think the description is a little weird with the high AC (why is this furry / slimy thing with Dex 10 so hard to hit?).

I would personally go for something more trap-like; maybe some kind of psychic barnacle to justify the high AC, with a speed of like 5 or 0. Making them immobile also contrasts nicely with your highly-mobile grapple-devourers. Killing all the intellect devourers in an area means very little because they can teleport at any time, but killing all the observers in an area means you have a safe space to recuperate for at least a day or so.

[sandmote]

As a general note, I hope you're having a problem with the martial PCs dealing a lot of damage, given you're mostly giving the mind flayers AC and melee damage, and making the Observes so dificult to hit with an arrow.


Illithid carapace armour: Thick, bony chitin plates overlapping an illithid's skin. Acts as +2 full plate when bonded to an illithid, raising their AC to 20.

Mind-killer rifles: Psionic rifles that automatically home in on a target's mental energy. These can be fired outside of line of sight as long as the firer is linked to something that does have line of sight on the target (like an intellect devourer). Deal 4d6 + 16 psychic damage, or half on a DC 15 Int save. Range is 300 feet.

Psi-blades: Blades of glowing psionic force, lancing out from the mind flayers gauntlets. Deals 3d6 + 4 force damage, but the mind flayer can make two attacks. Defensively you're boosting the AC by 5. Boosting AC over the expected value is +.5 to defensive CR per point of AC. Offensively, giving up the grapple/stun/eat brain combo for four attacks using the Psi-blades is overall weaker but more consistent. +1 to total CR, effectively +2 inside an Observer's field where the rifles and mind blast deal more damage.


Death burst: when the intellect devourer hits zero hp, it explodes. 4d6 psychic damage, Int save DC 15 halves

Grapple: the intellect devourer sprouts tentacles and makes an attack. +4 to hit, zero damage, and the target is automatically grappled (escape DC 15).

Teleport: the intellect devourer can teleport itself 50 feet as a bonus action, or teleport itself and a grappled target 30 feet as a bonus action.

Psionic Link: the intellect devourer can psionically link with any mind flayer wearing a soulsight helm within 500 feet of it, allowing the mind flayer to see and hear what it hears. The grapple might be cool, but its subpar as a combat option. The teleportation out from behind cover into the open (where illithids can now see the party member) might be a cool combat piece though. To allow counterplay, I'd reduce the range of the teleports, so the devourer needs to run up and then teleport (warning the party its there) and can't teleport a grappled target far enough to make them surrounded by the enemy out from behind cover is probably far enough of a teleport into additional danger).


Hit points: 5
AC 25
All abilities and saves: +0, no proficiencies.
Speed: fly 50' (hover) In practice this thing is horribly difficult for a martial character to take out, and very easy for a caster with spells which use saving throws. I assume its meant to be used in tandem with a Mind Flayer wielding a Mind-Killer Rifle, in which case I hope the weakness to casters and heavy resistance to martials in intended. Between this AC and the range of their field, does this mean someone in the party has the Sharpshooter feat?


Emit Disruptor Field: Anyone within 200 feet of the observer has vulnerability to psychic damage, and disadvantage on Intelligence and Wisdom saving throws. Okay, so 5 HP gives a base defensive CR of 0, and you increase it by 6 increments due to its AC of 25, to a total defensive CR of 3. If we treat the attack from the Mind-Killer rifle as being used through the Observer as part of the Observer's damage output (since the illithid is presumable out of range otherwise), the Observer averages 60 damage per round and inflicts disadvantage on the saving throw to avoid the rifle. Total CR of 7 or so, much lower for casters with saving throws if they can reach the observer with their attacks, damage effectively being halved if they're only buffing an illithid's attacks instead of letting it attack something otherwise out of the illithid's range.

I'm going to suggest reducing the range to 60 feet. The party will still need an action (or at least an attack) to deal with one, but the Observer will need to be close enough for the party to interact with. With the current range I worry the experience will be that the party is just constantly stuck with the Disruptor Field, dashing their way to find the Illithid snipers wielding Mind-Killer Rifles. If you force the Observer closer to the party so they can kill it and then have more Observers moving in (one entering range either once per round or once every other round), the party can choose between trying to disable the snipers each round verses bum rushing the sniper's positions.

This was written before I saw Just to Browse's comment, and the barnacle observers might work as well. With 'barnacle' observers though I worry the party won't really be able to tell the observers they see on the walls are allowing the illithids to start sniping, whereas a flying creature showing up right before the shooting starts will hopefully be a clear signal the two are intertwined.

[Yakk]

I'd have the Mind Flayers riding creatures like mounts. The mount's brain is exposed and modified, and the mind flayer controls it with tentacles. The mind flayer could even mount within the body of the creature. Killing the armor ejects the Mind Flayer.

5e is mostly a linear game. Enough CR 7 creatures will cream even a massively OP party (unless we are talking greater than +3 magic items).

The combat-armor could be built at CR 8-10, with psi blades etc. Could be umber hulk based (but augmented).

But I like the idea of mind blast intellect devourer grenades.

[Isocahedron]

I don't know enough to really comment on your homebrew, but you might want to watch this video: https://www.youtube.com/watch?v=5SvYXnbnz8Q. The mind flayers' INT score can be the most dangerous part of their statblock.

[Ionathus]

I think most of the intellect devourer and the observer changes are fine -- they'll make it more challenging and interesting and they don't feel like B.S. to me. I'd cap the teleport for the intellect devourer at 1x/day or else it could get REALLY tedious.

I'd shorten the range on Emit Disruptor Field to something like 30 or even 15 feet, and give it a very short duration (and limited uses per day): vulnerability to psychic damage and disadvantage on INT saves is basically a death sentence in a mind flayer colony, so you want that to feel like an "emergency weakness" rather than a "permanent environmental effect" -- which is what it'll feel like with a 200-foot range and seemingly at-will usage.

However, I object to the first three of your actual Mind Flayer changes. If a Mind Flayer is taking hits in melee, or trying to deal hits in melee, it's already lost. It doesn't matter how cool the sword is; when you've got a signature ability called "Mind Blast", using your action to swing a sword is a waste of your talents1. Mind Flayers are built to be watchers in the shadows, manipulators, mind-controlling slave masters, lurking apex predators who kill their prey in intricate ambushes. Mind flayers don't pull out a psi-sword and start swinging: they hide behind minions and spring traps and overwhelm their opponents with psionic attacks from a distance, then they close in to finish off debilitated/captured prey in a manner similar to those snakes that hunt using venom and patience.

I'd suggest giving them abilities to complement that playstyle, such as a "commander" ability to buff their minions, or an ability that lets them get to captured/stunned PCs faster to start brain-sucking, or an emergency teleport ability they can use to disengage with any melee fighters lucky enough to close the distance.

Always put them with mind-controlled minions (and hey, go crazy with the minions and give them all those combat-focused homebrew items you were gonna give the flayers themselves), and let the minions do the hacking and slashing, and hey, now you've designed super interesting and effective encounters where the PCs have to come up with ways to avoid the minions and pin down the high-value mind flayer commanders, while not getting tagged with anything too debilitating themselves...because they'll learn from experience that getting caught in a mind flayer web is a one-way ticket to brain-slurp town.

1. Some may point out that Mind Blast is a Recharge 5-6 and thus can't be used every turn, so the Mind Flayers need something else to do in the meantime: honestly, I don't see it. Again, in my mind these things fight like vipers: make a single powerful bite, wait for it to take effect, don't engage until your prey is so incapacitated it can't fight back. Simple, clean, ruthless, utterly unfair -- perfect characterization for a mind flayer. So what if it has a few "dead" turns while it waits for its mind blast to recharge? It can hide, it can command its minions, it can activate a stray magic item or drink a healing potion or heck, it can just Dodge. It's not in a hurry -- it has all the time in the world. It's got high enough Intelligence to know that getting up close and personal with the tin can holding a greatsword is a bad idea when you possess a squishy octopus head.