Is taking down a mind flayer colony impossible in practice?

[rondragon123]

Thinking about making a campaign focused on taking down a mind-flayer colony
but given that they have dominate monster 1/day for each one, and that they are acting as a hivemind, I really don't see how even a 4 max level party can take a full colony down. Am I missing something or is this truly impossible?

[MaxWilson]

Thinking about making a campaign focused on taking down a mind-flayer colony
but given that they have dominate monster 1/day for each one, and that they are acting as a hivemind, I really don't see how even a 4 max level party can take a full colony down. Am I missing something or is this truly impossible?

Counterspell, Paladin of Devotion (prevents charm and therefore prevents domination), Darkness/Greater Invisibility (prevents being seen and therefore prevents Dominate Monster), and Mind Blank come readily to mind.

And of course you can always starve them to death. Use ranged weaponry + mounted combat to shoot them to death from way outside spellcasting range whenever they come out of their colony, and they won't get any fresh brains. Eventually they'll have to all leave via Plane Shift to avoid dying, but Plane Shift isn't precise enough for them to come back to the colony while avoiding your siege forces.

The siege approach would be appropriate if there were thousands of mind flayers in the colony. If there were only dozens you could just storm it with high-level PCs under Darkness/Mind Blank/etc.

[Xihirli]

Protection from Evil and Good is a first level spell.

[Protolisk]

Max level parties have options like Divine Intervention, multiple 9th level spell slots, and barbarians and moon druids who are near impossible to kill. At extremely high levels a colony attack could be easy. If a party built their characters organically and knew they were up against ilithids, or you told them ahead of time for a one shot, they can easily plan ahead for the Int saves via wizards, Resilient (Int), or spells like Mind Blank to make their heaviest hits ineffective, or the Cha saves in similar manners.

[rondragon123]

Counterspell, Paladin of Devotion (prevents charm and therefore prevents domination), Darkness/Greater Invisibility (prevents being seen and therefore prevents Dominate Monster), and Mind Blank come readily to mind.

what about mind blast? a full colony of mind blasting creatures will surely be too much even for what you said.

[LudicSavant]

what about mind blast? a full colony of mind blasting creatures will surely be too much even for what you said.

Mind Blast is Save Negates, and only DC 15. So for example, a Wizard with +5 Int, +6 proficiency, and +3 to saving throws would make that 100% of the time.

Anyways, how big is this colony we're talking about?

[darknite]

Mind Blast is Save Negates, and only DC 15. So for example, a Wizard with +5 Int, +6 proficiency, and +3 to saving throws would make that 100% of the time.

Anyways, how big is this colony we're talking about?

That's nice for the Wizard. Everyone else will fail at one point or another.

[LudicSavant]

That's nice for the Wizard. Everyone else will fail at one point or another.

What part of "for example" made you think "this is literally the only way to do it"?

[MaxWilson]

what about mind blast? a full colony of mind blasting creatures will surely be too much even for what you said.

How many illithids are in your hypothetical "full colony", dozens or thousands? Mind Blast is a nice, medium-ranged AoE against a save that is weak on most PCs and monsters, but after a whole campaign focused on illithids I wouldn't count on PCs not adapting. (Paladin auras, Bardic Inspiration, Bless, etc.) Then it's just a question of numbers. Dozens shouldn't be a problem for max-level PCs, especially if they find a way to defeat them in detail. And there's always Meteor Swarm...

That's nice for the Wizard. Everyone else will fail at one point or another.

So the Paladin fails a save 10% of the time (for example--exact numbers will vary), so if he ever faces ten Mind Flayers at once he is likely to get stunned. Why does this make you think the campaign is impossible? Again, how many mind flayers are we dealing with here? Unless the answer is "thousands", failing the occasional save vs. Mind Blast will not defeat the PCs.

If the answer is thousands, they should switch to siege tactics and starve the mind flayers of brains.

[LudicSavant]

How many illithids are in your hypothetical "full colony", dozens or thousands? Mind Blast is a nice, medium-ranged AoE against a save that is weak on most PCs and monsters, but after a whole campaign focused on illithids I wouldn't count on PCs not adapting. (Paladin auras, Bardic Inspiration, Bless, etc.) Then it's just a question of numbers. Dozens shouldn't be a problem for max-level PCs, especially if they find a way to defeat them in detail. And there's always Meteor Swarm...

This.

Heck, Resilient (Int) + Paladin Aura + Bless is already +12-15 to Intelligence saves. Throw on a Cloak of Resistance and a 12 Int and you're fully IP-proofed against all those pesky Intellect Devourers and Mind Blasts and so forth. Not "truly impossible" at all.

And there are many other ways of being able to approach large groups of foes, too. Divide and conquer, siege, vision control, all kinds of things. And actually killing high level adventurers is harder than just extracting a brain from their skull; high level PCs have access to a variety of "cheating death" type abilities.

[nickl_2000]

We are talking a Max level PC party who knows the location of a Mind Flayer colony? At that point they would just go recruit a whole boatload of Gith and just sit back and watch the chaos. By level 20 you should have communications with other planes and you can bring some in.


Other than that, hit and run with ranged attacks further out than a Flayer can hit (Spell Sniper and Ranged weapons should be able to do this). Counter Spell and Dispel Magic as other

[Xihirli]

Mind Flayers do not have a lot of hit points, and their AC isn’t very good for late tiers. The thing about them is they can be very dangerous when their stuff lands: dominate monster is very powerful, and the Stun is pretty good too. But late tiers alter that a lot. By the time you hit level 12 you’ve probably figured out how to prepare for domination effects. Raging berserkers can’t be charmed, Samurai have WIS proficiency and Indomitable, Wizards are pretty safe and can give another party member complete immunity to being charmed by aberrations. Druids have INT/WIS, Paladins have absurd WIS saves, and high level rogues also have WIS/INT.
At lower levels the stun is pretty scary but at high tiers when your friends can kill a mind flatter pretty quick after the stun it’s less of an issue.
I had two level 15 characters going through a colony trying to capture the elder brain. I gave the colony multiple ulitharids, a mind witness, two brainsteeler dragons, several dozen minions of varying types (enslaved lizard folk, grell, those walking brain things) and even included a Tarrasque in there for fun. Neither of the players dropped and none were dominated for more than a round before the other killed the offending mind flayer. Because I told them it was a mind flayer one shot and they prepared for it.
Both in and out of universe, Illithid are very dangerous to spring on people not ready for them but if you’re specifically preparing for them they’re not so tough. Just ask the Gith.

[Ason]

In older editions one common tactic against mind flayers was using golems and undead minions. If I recall, those creatures were flat-out immune to most mental attacks and could simply bash squid-faces into bloody pulps. It's tough to use mental powers against something that doesn't have a mind to begin with.

In 5e, most undead lose their psychic protections save for the revenant (which gets resistance to psychic) and certain boss level undead monsters (who you'd have a hard time recruiting or creating). But constructs (golems, clockwork creatures, animated weapons/armor/etc) are often still immune to psychic damage and charm effects and also lack brains, which makes them perfect minions for cleaning out mind flayer colonies. The big remaining problem your construct minions would have is mind flayers' ability to levitate at-will. I think animated weapons and the like have a fly speed though, so you might be able to use those to harass flying flayers while golems take out anything left on the ground. Flayers usually design their colonies to force attackers to use levitation to get around, however, so most constructs would have difficulty navigating but could effectively shut down a level from flayer control once they get there.

So to answer your question, in my opinion the easiest way to clear out a mind flayer colony is to have a wizard/artificer build some constructs, send those things in ahead of the party, and then have the wizard's party come up behind the constructs to deal with any unusual problems, give new orders, investigate, etc.

[KorvinStarmast]

We are talking a Max level PC party who knows the location of a Mind Flayer colony? At that point they would just go recruit a whole boatload of Gith and just sit back and watch the chaos. By level 20 you should have communications with other planes and you can bring some in.

This, right here. That's why the party accumulated all of that treasure ... to offer the Gith a bit of coin for the raid.

[darknite]

What part of "for example" made you think "this is literally the only way to do it"?

I'm expanding your point, not criticizing it.
So sure, Wizards would be cool, but that's hardly the base case. Yeah, stacking stuff like Auras and Bless and whatever are nice, but the fact is that Int is usually a dump stat for non-Wizards and a DC 15, unless you have extraordinary and persistent cover, is not a chump save. If you're facing dozens of illithids, the law of averages is going to get you.

[Imbalance]

Take off and nuke the entire site from orbit. It's the only way to be sure.

Is there an Elder Brain running this joint? That's as important a factor as the number of 'thids, because at some point you may have to admit you're playing Metroid and you'll have to give the players phazon beams or something.

[MaxWilson]

Take off and nuke the entire site from orbit. It's the only way to be sure.

This installation has a substantial gold piece value though.

[Imbalance]

This installation has a substantial gold piece value though.

They can bill me.

[NNescio]

The main issue is the Elder Brain's Creature Sense ability, which acts as a potent anti-intrusion system (unless there's a lot of unaccounted-for noise in the background , which is unlikely.) The first search party sent out to investigate will likely be easily-surmountable by the party, but after the Elder Brain is aware of the threat it can pretty much coordinate the entire colony against the party in a ridiculously efficient manner, like someone playing an RTS from a top-down perspective. Things get worse if one of the party (or a minion/pet) gets incapped (sleeping or getting stunned counts), allowing the Elder Brain to link to it and see through its eyes.

So, at minimum, every member of the party need to have Nondetection up. Minions too, except for those that can be tucked away in extradimensional space (a familiar hiding in a pocket dimension provides very good distraction when needed). Ideally you want Mind Blank but this is only available at L15, plus spell slots are limited.

After that, you want some way to shield against charm (and by extension Dominate) effects. Protection from Evil and Good is the usual standby, but you can't have it active all the time. The Archfey Paladin's Aura of Devotion is also nice, but relying solely on it can be risky because it forces the party into a certain formation. Calm Emotions will work nicely to temporarily suppress Charm effects so your party member can do its thing. Meanwhile Dispel Evil and Good and Greater Restoration can outright remove Charm effects. (but they are costly in spell slots to use.). Some way to boost saves would also be nice, as further insurance; Bless, Bardic Inspiration and the Paladin's aura work well here.

Construct minions are good to have around if you have the wherewithal to acquire them. The simplest way is via True Polymorph'd objects; Helmed Horrors are excellent for this purpose due to their long list of condition immunities. This does require a L17 caster though.

[Brookshw]

They can bill me.

Well played both of you.

Back to the OP, as people have demonstrated there are ways to deal with the mindflayers. What I'm wondering about are the thralls & minions that would also be about. MFs are smart and should keep things around to deal with enemies who are otherwise immune to the MFs. How strong those things are is up to you, but you should consider it carefully before the campaign concludes with the party casting a buff or two then chopping through a bunch of relatively weak squids.

[LudicSavant]

I'm expanding your point, not criticizing it.

Ah, I see.

[Willie the Duck]

Thinking about making a campaign focused on taking down a mind-flayer colony
but given that they have dominate monster 1/day for each one, and that they are acting as a hivemind, I really don't see how even a 4 max level party can take a full colony down. Am I missing something or is this truly impossible?

what about mind blast? a full colony of mind blasting creatures will surely be too much even for what you said.

There is nothing in these specific abilities that are specifically bad such that large numbers of them would be inherently more problematic for high-level adventurers than what they otherwise might face. Dominate is even something that PCs can gain temporary actual immunity from. Compare taking on a colony of a few dozen to maybe 50 mind flayers to taking on a colony/city of a several hundred human soldiers and frankly the humans might be more of a problem for a party of 4 level 20 characters. Mind you, at-will area effects are damn frustrating and my general advice is not to do this scenario (or at least expect that it will be solved with out-of-the-box thinking rather than direct confrontation) -- not because it would be impossible for the party, but because the whole thing might become an insufferable quagmire of checking distances and blast radii.

[NNescio]

There is nothing in these specific abilities that are specifically bad such that large numbers of them would be inherently more problematic for high-level adventurers than what they otherwise might face. Dominate is even something that PCs can gain temporary actual immunity from. Compare taking on a colony of a few dozen to maybe 50 mind flayers to taking on a colony/city of a several hundred human soldiers and frankly the humans might be more of a problem for a party of 4 level 20 characters. ...

Planar Bind/True Polymorph something with immunity to nonmagical attacks. Sic it on the human colony while you and your mates sip martinis and watch the spectacle with Scry-Teevo. Cackle evilly all the way.

Or, yannow, just Mirage Arcane the whole place. Or Shapechange/True Poly into a dragon (shadow for added !!FUN!!) and burn down the whole place, if you want to be hands-on for some reason. Remember to have a friend (or Sim) with Dispel if you go with True Poly.

[Grod_The_Giant]

what about mind blast? a full colony of mind blasting creatures will surely be too much even for what you said.

Counterargument: Meteor Swarm has a one-mile range and deals enough damage to one-shot a 'flayer on a successful save.

[nickl_2000]

Counterargument: Meteor Swarm has a one-mile range and deals enough damage to one-shot a 'flayer on a successful save.

Does Meteor Swarm work underground?

[Tharkun]

A wizard with time to prep can set up multiple glyphs of warding that cast mind blank in a demiplane. That solves all of the domination/psychic damage issues.

Wizards and Paladins are very useful in this circumstance. This could be a blast to do. Someone might die in the end but I see the colony going down.

[Tharkun]

Does Meteor Swarm work underground?

Yes.

Blazing orbs of fire plummet to the ground at four different points you can see within range. Each creature in a 40-foot-radius sphere centered on each point you choose must make a Dexterity saving throw. The sphere spreads around corners. A creature takes 20d6 fire damage and 20d6 bludgeoning damage on a failed save, or half as much damage on a successful one. A creature in the area of more than one fiery burst is affected only once.

The spell damages objects in the area and ignites flammable objects that aren't being worn or carried.

[NNescio]

Yes.

Blazing orbs of fire plummet to the ground at four different points you can see within range. Each creature in a 40-foot-radius sphere centered on each point you choose must make a Dexterity saving throw. The sphere spreads around corners. A creature takes 20d6 fire damage and 20d6 bludgeoning damage on a failed save, or half as much damage on a successful one. A creature in the area of more than one fiery burst is affected only once.

The spell damages objects in the area and ignites flammable objects that aren't being worn or carried.

It does, but it's not going to be very useful underground unless there's one big cavern where all the squidfaces congregate for some reason.

Maybe the party can scout out the place and bait all of them into a convenient location, but that's a dicey proposition.

[Willie the Duck]

Does Meteor Swarm work underground?

AFAICT, nothing in the spell description precludes it.

Planar Bind/True Polymorph something with immunity to nonmagical attacks. Sic it on the human colony while you and your mates sip martinis and watch the spectacle with Scry-Teevo. Cackle evilly all the way.

Swap out immunity to nonmagical attacks with immunity to psychic abilities, and you've just solved the illithid problem, so I don't really think that changes the illithid vs. human colony math. Regardless, I'd put that in the out-of-box strategies I'd expect to see in these scenarios. It is really the...

Or, yannow, just Mirage Arcane the whole place. Or Shapechange/True Poly into a dragon (shadow for added !!FUN!!) and burn down the whole place, if you want to be hands-on for some reason. Remember to have a friend (or Sim) with Dispel if you go with True Poly.

...hands-on scenario like this that I think the OP was talking about (given that he was worried about the illithids' dominates and mind blasts).

[MaxWilson]

Planar Bind/True Polymorph something with immunity to nonmagical attacks. Sic it on the human colony while you and your mates sip martinis and watch the spectacle with Scry-Teevo. Cackle evilly all the way.

Or, yannow, just Mirage Arcane the whole place. Or Shapechange/True Poly into a dragon (shadow for added !!FUN!!) and burn down the whole place, if you want to be hands-on for some reason. Remember to have a friend (or Sim) with Dispel if you go with True Poly.

Dispel is not needed--attacking yourself until you hit 0 HP does the same thing.

...hands-on scenario like this that I think the OP was talking about (given that he was worried about the illithids' dominates and mind blasts).

Covered by Mind Blank, Int save proficiency (with Shapechange at least), and legendary resistances (unlike legendary active you do get these when Shapechanging), plus you don't have to end your turns in Mind Blast range because you fly 80' and have reach weapons.

What I'd be most worried about in this scenario is a thrall or mind flayer arcanist with Dispel Magic. There goes Shapechange, there goes Mind Blank, now you have to teleport away or it's Welcome To the Collective.