Mind flayer

The mind flayer, h, is an especially perilous type of monster that appears in NetHack. They are omnivorous humanoids with octopus-like tentacled heads, and possess flight, telepathy, see invisible, and infravision. The mind flayer can use its tentacle attacks to eat its victims' brains, draining intelligence and abusing wisdom while often inflicting amnesia - losing enough intelligence this way can be irreversibly fatal.

A mind flayer can grow up into a master mind flayer, h; both share a colored glyph with the dwarf king, h. Eating their corpses can grant telepathy or raise intelligence by 1 point, with a 50% chance of each.

The following information pertains to an upcoming version (NetHack 3.7.0). If this version is now released, please verify that it is still accurate, then update the page to incorporate this information.

Mind flayer tentacle attacks no longer cause amnesia.

Other common traits

Mind flayers move at the same speed as an un-hasted, unburdened player character, and can wear all armor will occasionally concentrate and release a blast of psychic energy, and can sense if you have telepathy yourself—"a faint wave of psychic energy" is a sign that one is present on the level. If you have telepathy and are within sight or telepathy range of a mind flayer that is hostile or under the effects of conflict, it will "lock on" to your mind or telepathy for d15 damage; this damage is halved with half spell damage. With a peaceful or tame mind flayer, the blast will "feel quite soothing" and no damage is done.

Generation

Randomly-generated mind flayers and master mind flayers are always generated hostile. They are also valid polymorph forms, meaning that you may encounter one far earlier in the dungeon either as the guise of a shapeshifter or the result of a polymorph trap.

Both types of mind flayer are notorious for potentially generating upon entering a floor of the Gnomish Mines, where they are normally far too high difficulty to appear. These "minesflayers" are the result of the Mines levels specifying that one random h monster should be generated at normal level creation; this is almost always a dwarf, hobbit, or bugbear. On occasion, however, the function that chooses which ​h monster should be generated totally ignores the difficulty of the monster it produces and creates a (master) mind flayer.

Descriptions

• Mind flayer
• Master mind flayer

h mind flayer
Difficulty	13
Attacks	Weapon 1d4, Tentacle 2d1 int drain, Tentacle 2d1 int drain, Tentacle 2d1 int drain

h mind flayer
Difficulty	13
Attacks	Weapon 1d4, Tentacle 2d1 int drain, Tentacle 2d1 int drain, Tentacle 2d1 int drain
Base level	9
Base experience	263
Speed	12
Base AC	5
Base MR	90
Alignment	−8 (chaotic)
Frequency (by normal means)	1 (Very rare)
Genocidable	Yes
Weight	1450
Nutritional value	400
Size	Medium
Resistances	none
Resistances conveyed	Telepathy (50%), +1 Intelligence (50%)
A mind flayer: can fly. has a head, a couple of arms, and a torso. can see invisible creatures. is omnivorous. is normally generated hostile. is nasty. likes gold. likes gems. can pick up weapons and food. has infravision. can be seen through infravision.
Reference	monst.c#line449

The mind flayer has a base AC of 5, and is likely the variety a player will encounter first.

h master mind flayer
Difficulty	19
Attacks	Weapon 1d8, Tentacle 2d1 int drain, Tentacle 2d1 int drain, Tentacle 2d1 int drain, Tentacle 2d1 int drain, Tentacle 2d1 int drain

h master mind flayer
Difficulty	19
Attacks	Weapon 1d8, Tentacle 2d1 int drain, Tentacle 2d1 int drain, Tentacle 2d1 int drain, Tentacle 2d1 int drain, Tentacle 2d1 int drain
Base level	13
Base experience	416
Speed	12
Base AC	0
Base MR	90
Alignment	−8 (chaotic)
Frequency (by normal means)	1 (Very rare)
Genocidable	Yes
Weight	1450
Nutritional value	400
Size	Medium
Resistances	none
Resistances conveyed	Telepathy (50%), +1 Intelligence (50%)
A master mind flayer: can fly. has a head, a couple of arms, and a torso. can see invisible creatures. is omnivorous. is normally generated hostile. is nasty. likes gold. likes gems. can pick up weapons and food. has infravision. can be seen through infravision.
Reference	monst.c#line457

The master mind flayer has a base AC of 0 and a stronger weapon attack, along with 5 tentacle attacks; it is identical to its previous form in many aspects.

Generation

In addition to the above, master mind flayers can be summoned by the summon nasties monster spell.

Strategy

Mind flayers and master mind flayers are considered a consistent, high-level threat throughout the entirety of the game due to the intelligence-draining attack, which has taught many an unfortunate lesson to players. Brainlessness is an instadeath that ignores not only your current HP, but lifesaving as well—you will be brought back, only to immediately die again since your brain is still gone. If you die from intelligence drain while polymorphed, you will also permanently die instead of reverting to your normal form. This makes mind flayers and their 'master' forms common targets for genocide, as well as stellar pets for those who can procure a tame flayer.

If in explore mode or wizard mode and you choose not to die of brainlessness, your intelligence is then boosted by two points.

Detection

If you start sensing waves of psychic energy, that is your cue to farlook and check whether any h you encounter is a dwarf—a somewhat common YASD is to mistake the mind flayer for an easily-killed dwarf king, then march in and have your brain promptly eaten. If you have telepathy, blinding yourself temporarily (e.g., via blindfold or towel) can be used to quickly confirm if a flayer is present on a level; dwarves also do not generate randomly inside Gehennom, making detection there more trivial.

Combat

When fighting mind flayers, avoid melee-range combat if at all possible, especially if you are burdened and/or have low intelligence. Mind flayers respect Elbereth and can be deterred by standing on a scroll of scare monster, though the former will not work in Gehennom. A flayer's 90 MR will often stop all but the more powerful spells available that manage to hit through their AC, and makes scaring them through other means a difficult task.

An expensive camera or tooled horn, while not as secure as Elbereth for the above reasons, can still frighten off mind flayers, especially in Gehennom where Elbereth is of no use. Beware that a fleeing mind flayer may still attack you, although it is much less likely to; additionally, a blinded one will not respect Elbereth. Scaring a mind flayer also does not prevent them locking on to your mind or telepathy.

Cancellation will not affect their brain-sucking attacks even if it successfully hits; projectiles such as daggers or arrows are among your best resources to consistently deal damage. Alternately, if your ranged attack options are limited and melee is your only out, consider stoning them or taking other measures to prevent or minimize stat loss (discussed in more detail below).

Preventing intelligence drain

Wearing any greased helm prevents the mind flayer's tentacles from reaching your brain, but the grease has a ¹⁄₂ chance to wear off with each attack; a non-greased helm has a ⁷⁄₈ chance of preventing each of the mind flayer's tentacle attacks. Mind flayers get multiple attacks per turn, so you should not rely solely on a greased helm, especially if you are unable to kill them quickly. Alternate possibilities include wearing a dunce cap or ring of sustain ability; both items will fix your intelligence stat (either at 6 or its current value), preventing stat loss and thus brainlessness, on top of the dunce cap's chance to block the tentacles. A blessed unicorn horn or potion of restore ability can also reverse the stat loss fairly quickly.

Polymorphing into a headless monster will protect you from the intelligence drain attacks, which can mitigate the worst of their threat; polymorphing into a normally mindless form will not protect you - as a comment in the relevant code says, players aren't mindless.

None of these methods will prevent amnesia from a successful brain-sucking, and you're likely to come out of the fight very forgetful—have a means of re-identifying items on hand if possible. You can use #name to label one of a particular type of item(s) that you consider vital and/or does not auto-identify as a precaution.

The following information pertains to an upcoming version (NetHack 3.7.0). If this version is now released, please verify that it is still accurate, then update the page to incorporate this information.

In addition to mind flayer attacks no longer causing amnesia, unicorn horns will no longer restore lowered stats.

Genocide

While the amnesia and instadeath from brain-eating are enough to make both forms of mind flayer a popular target for genocide, do not attempt blessed genocide of mind flayers if you are a dwarf! Using a blessed scroll of genocide will remove all h from the current game including dwarves, serving as a particularly aggravating YASD for forgetful dwarven players.

One or two "normal" genocides, either from the uncursed scroll or a throne, should be used instead; the master mind flayer should ideally be targeted first, as regular mind flayers cannot be generated via summon nasties unless they randomly replace an extinct/genocided nasty.

You should ideally always identify the beatitude of possible scrolls of genocide before reading, but this is especially true if you plan to eliminate mind flayers with one—that randomly read scroll you just found may be cursed, and the summoned horde of mind flayers will often result in a quick death, and even if you can scare them away, their psychic blasts may still overwhelm you. Also, be sure to mind your spelling, especially if you are a Monk—misspelling it as "master mindfalyer" will only parse the word "Master", one of the Monk's rank titles, and wipe out all monks including you.

The following information pertains to an upcoming version (NetHack 3.7.0). If this version is now released, please verify that it is still accurate, then update the page to incorporate this information.

If a genocided monster with a pre-grown form (that is not explicitly a baby form) is chosen, and this form is not also genocided, it will appear in place of the genocided monster. For example, mind flayers can appear in place of genocided master mind flayers. This also happens if the chosen nasty is inappropriate for the location, such as an arch-lich outside Gehennom.

As pets

While highly desirable as pets, taming a mind flayer is extremely hard and dangerous due to their monster magic resistance; you may be much better off using a polymorph trap on your current pet. Tame mind flayers make quick work of shopkeepers, and their telepathic outreach only locks onto and damage hostile monsters - the harmless message produced otherwise can be hidden with MSGTYPE. Remember that only tame and peaceful mind flayers will produces soothing waves—if you see different messages related to psychic waves and are taking damage from them, and you are not generating conflict, then a hostile mind flayer may be on the level.

Be especially careful if your tame mind flayer becomes confused—they will turn those psychic waves on you! This also makes conflict similarly perilous, although their high monster magic resistance ensures that once a mind flayer reaches level 15, it will become immune to conflict - and thus no threat to you or your brain matter should you decide to use it.

Tame flayers excel at killing many other monsters due to their tentacle attacks: non-mindless monsters take an additional d10 of damage per brainsucking attack to simulate brain loss. However, there are a few monsters that in turn pose a serious threat should a mind flayer attempt to eat their brain:

• Cockatrices, chickatrices and Medusa will turn a mind flayer to stone if a tentacle attack lands.
• Jellies have passive attacks that can easily rack up enough damage to kill an unlucky mind flayer attacking one.
• Shapeshifters and green slimes are similarly dangerous: the former may go down quickly, but will polymorph a mind flayer that eats its corpse, while the latter is extremely likely to turn it into another slime.
• Riders that mind flayers target are immediately fatal if they manage to eat one's brain, though the Rider in question still takes the extra "brain loss" damage.

Ochre jellies are a common sight in the late game, especially as a summonable nasty—consider giving your mind flayer any yellow dragon scales (or dragon scale mail) that you happen upon to provide them with valuable acid resistance.

Mind flayers also have a tendency to attract covetous monsters with their psychic blasts; if approaching the goal level of your Quest, the Wizard of Yendor's Tower or one of the many demon lairs of Gehennom, you may want to leave them on another floor temporarily. Alternately, if you intend to draw covetous foes to the up stair this way, be prepared accordingly; in particular, a mind flayer pet or polyform can be used by Rogues on their quest to awaken the Master Assassin, who will then warp from his otherwise inaccessible dwelling.

The following information pertains to an upcoming version (NetHack 3.7.0). If this version is now released, please verify that it is still accurate, then update the page to incorporate this information.

From commit 0891ef4: Monsters wearing alchemy smocks now additionally gain acid resistance instead of just poison resistance, allowing for more flexibility in kitting out a tame mind flayer. Additionally, per commit 2cad4ec, each individual covetous monster will pick either the upstairs or downstairs to warp to.

As a polymorph form

The master mind flayer is a very sought-after form for polyself: on top of flight, multiple attacks per turn, 0 base AC of 0 and no changes to armor or encumbrance, its brain-eating attack is deadly to nearly anything. When eating a monster's brain, you gain d30 nutrition per successful tentacle attack and exercise wisdom, without risk of choking; if your intelligence is below its current maximum (e.g., your own brain was sucked), it will be increased by d4. The intelligence increase is subject to the normal polymorphed attributes rules, and will be reset when you revert to your normal form; among its few drawbacks are that your max HP may also drop significantly in this form, especially if polymorphing at a high level. The master mind flayer form also sees use in speed ascensions, especially with Valkyries.

Naturally, players in mind flayer form face the same dangers as pet mind flayers, including potential death from triggering too many passive attacks. Furthermore, brainsucking a green slime causes delayed sliming, and eating a cockatrice's brain causes both immediate stoning and delayed stoning if the immediate stoning was stopped by an amulet of lifesaving. Sucking the brains of your race or other mind flayers will count as cannibalism as well, though this does not trigger a penalty for each individual brain-sucking attack - for Monks and vegan or vegetarians players, eating brains will also break those conducts. While you cannot choke directly from eating brains, you can become satiated—you will not receive a warning when oversatiated, and thus run a significant risk of choking from eating anything afterward, which is an instadeath even while polymorphed.

History

The mind flayer first appears in NetHack 3.1.0, and the master mind flayer is introduced in NetHack 3.3.0.

From 3.1.0 to NetHack 3.4.3, including some variants based on them, the game would not recognize the alternate spelling "mindflayer" when selecting a monster for genocide. This meant that from 3.3.0 to 3.4.3, a Monk that attempted to genocide "master mindflayer" would instead genocide "master", thus wiping out all Monks and ending the game. As mentioned above, "master" is one of the rank titles for Monks, and the parser ignored the 'unfamiliar' word "mindflayer"; this was fixed in NetHack 3.6.0.

Master mind flayers are one of the many polyforms that can aid in pudding farming in earlier versions of the game where it was possible.

Origin

Mind flayers first appear in Dungeons & Dragons as illithids; creator Gary Gygax was reportedly inspired to create the monster after seeing cover art for a book by Brian Lumley.

Messages

The <master> mind flayer's tentacles suck you!

A mind flayer has hit you with its brain-sucking attack.

Your brain is eaten!

You lost intelligence and/or memory of items and floors to the brain-sucking attack.

Your <helm> blocks the attack to your head.

Your worn helmet successfully protected you from its tentacle attack.

You don't seem harmed.

You were protected you from the tentacle attack due to being in the form of a headless monster.

Your last thought fades away.

You died of brainlessness.

<Foo>'s brain is eaten!

A monster was hit by a mind flayer attack, and takes an extra d10 damage.

<Foo> doesn't notice.

As above, but the 'victim' was mindless and takes no extra damage.

<Foo>'s last thought fades away...

A monster was killed by the brain-sucking attack.

Ingesting that is fatal.

You ate the brain of a Rider while in mind flayer form, dying instantly and abusing wisdom if you are revived by an amulet of life saving.

You have a sad thought for a moment, then it passes.

A tame mind flayer was turned to stone from an attempt to eat a monster's brains.

Variants

SLASH'EM

Mind flayers are slightly different in SLASH'EM. First, the master mind flayer has three brain-eating attacks, while the normal mind flayer has five—an unusual reverse of the situation in vanilla NetHack. More importantly, though, the ring of free action provides luck-based protection against their brain-eating attacks, starting at a 50% of blocking each individual flay and increasing to a 90% chance at maxed-out luck. This, in combination with a greased helm, renders them much less of a threat.

Also, SLASH'EM introduces more sources of amnesia (such as potions of amnesia and migo queen attacks), making a preventative genocide of mind flayers much less of a surefire protection against amnesia.

Lastly, if you polymorph into an intelligent monster in SLASH'EM, generally you need not worry about petrifying monsters. This is true of mind flayers—instead of eating the cockatrice's brain and being stoned, you will instead simply not use your tentacle attack against it at all. Your weapon attack will still go forward, though, and it is still possible to get stoned by other methods (e.g. attacking it bare-handed).

SLASH'EM recognizes the "mindflayer" spelling, so it is okay to genocide "master mindflayer" in those games, but a typo like "master mindfalyer" will still wipe out all monks.

Encyclopedia entry

This creature has a humanoid body, tentacles around its
covered mouth, and three long fingers on each hand. Mind
flayers are telepathic, and love to devour intelligent beings,
especially humans. If they hit their victim with a tentacle,
the mind flayer will slowly drain it of all intelligence,
eventually killing its victim.