Intelligence drain

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This article is about the damage type that can leave a victim brainlesss. For monsters that have no brain, see mindless.

Intelligence drain, also known as drain intelligence, is a damage type that appears very rarely in NetHack, and uses the flag AD_DRIN.

The only monsters with the intelligence drain damage type are the mind flayer and master mind flayer, who both use it for tentacle attacks which are flavored as literally consuming the brains of a hero or monster that they hit in melee—these brain-eating attacks make both monsters infamously deadly foes.

Description

There are differences between intelligence drain attacks functions against a hero and against monsters, as monsters lack a formal intelligence attribute.

Eating the hero's brains

When an intelligence-draining attack targets the hero, it checks for a worn helm:[1][2] if the helm is greased, the attack will fail with a 23 chance for a cursed greased helm, and will always fail otherwise;[3][4] the grease then has a 12 chance of wearing off after the attack.[5] If the helm is not greased, it still has a 78 chance of blocking the attack.[6] A hero polymorphed into a monster that is immune to having their intelligence drained or else lacks a head entirely will not be affected by the attack.[7]

Otherwise, if the attack is not blocked by a worn helm, then damage is dealt that is subject to half physical damage but is not reduced by negative AC[8]—the attacker will then attempt to eat the target's brains, which is not affected by cancellation or blocked by magic cancellation:[9][10][11] the attack drains 1-2 points of intelligence, abuses wisdom and causes amnesia, which removes 14 of known level maps and 14 of discovered objects from the hero's memory[12][13]—a worn dunce cap or ring of sustain ability will prevent intelligence loss, but not amnesia.[9] A pet mind flayer or master mind flayer that eats the hero's brains this way gains nutrition, though in practice this will only occur if they are subjected to conflict, which is made highly unlikely by their natural 90 MR score and monster level.[14]

The brain-eating attack can still fail to apply its secondary effects against a mindless or non-corporeal target, but two factors specifically prevent this for the hero:[15] they are never considered mindless, and they cannot transform into any type of ghost.[16][17]

A hero in the form of a monster that causes stoning on contact or eating (i.e. a footrice) will have a chance of their brain being eaten by the attack as normal, followed by the attacker turning to stone[18]—a monster that has an amulet of life saving trigger as a result will abort its attack sequence.[19] This behavior is bugged for both types of mind flayer: if they miss their initial melee attacks, but successfully eat the hero's brain at any point, the rest of the attack sequence will proceed as normal despite the mind flayer being turned into a lifeless statue.

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

Brain-eating attacks no longer cause amnesia.

Per commit 2f255560, the chance of resisting conflict now depends on the hero's charisma, the monster's level, and the hero's experience level. Conflict is resisted if rnd(20) > min(19, (ACURR(A_CHA) - mtmp->m_lev + u.ulevel)) - thus, there is always at least a 5% chance of resisting it. Conflict also now requires that the monster see the hero, rather than the monster being in their line of sight. These changes are imported from SporkHack.

Becoming brainless

If intelligence loss from a brain-eating attack would occur when the hero's base intelligence (i.e. unmodified by any worn item such as a helm of brilliance) is at the minimum of 3, the hero suffers instant death from becoming brainless:[20][21] life saving that triggers at this point will resurrect the hero as normal, but they will instantaneously die again without a brain to keep them alive.[22] This can occur even when the hero has sustain ability, if their intelligence is already at the minimum. The only means of surviving death by "brainlessness" for the hero is in explore mode or wizard mode, where the player can decline when prompted for the hero to die: this will restore the hero's base intelligence to 5 before subtracting intelligence from the successful attack, and prints a message.

Eating a monster's brains

When an intelligence-draining attack targets another monster, it checks if the defending monster has a head, dealing no damage if they are headless.[23] It then checks for a worn helm, which blocks the attack 78 of the time.[24] If the attack is not blocked, the monster then has its brains eaten:[25] a non-corporeal or mindless monster will be unharmed, while all other monsters take up to 10 points of additional damage.[26][27][28] Monsters whose flesh causes stoning when eaten will turn the attacker to stone after the extra damage is inflicted, while monsters whose flesh causes sliming will cause nine turns of delayed sliming for the hero and instantly turn monsters into green slimes.[18] Attacking the Riders this way will kill the attacker after the extra damage is dealt.[29][30] When a monster is killed by extra damage from intelligence drain, the game will print a similar message to the one used for a hero dying of becoming brainless.[31]

A hero in the form of a mind flayer or master mind flayer that consumes a monster's brains this way exercises wisdom, has their hunger reduced by up to 30 for each successful attack and restores any lost intelligence up to their current maximum.[32][33] This naturally breaks vegetarian conduct, and the hero cannot choke this way, though they are still subject to potential cannibalism penalties (which are applied once per set of brain-eating attacks).[34] A pet mind flayer or master mind flayer that gains nutrition from eating the brains of a non-minion monster gains up to 60 nutrition per successful attack.[14][35]

Strategy

The threat of becoming brainless is enough to deter most heroes from attacking either type of mind flayer in melee if at all possible, and in a pinch they may even be worth a charge from a wand of death or stoning with a footrice corpse. Greasing a worn helm is also a common defense in case a mind flayer gets close, and some players may even resort to polymorphing their hero into a headless form as a last resort. While a blessed unicorn horn or a potion of restore ability can reverse the stat loss fairly quickly, the amnesia cannot be prevented if the brain-eating attacks land: have a means of re-identifying items on hand if possible, and consider naming and labeling one item each from a particular item type that either is considered vital or does not auto-identify itself as a precaution.

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

Unicorn horns will no longer restore lowered stats.

Genocide

Both the amnesia and instadeath from brain-eating are enough to make both forms of mind flayer popular targets for genocide—with this in mind, do not attempt blessed genocide of mind flayers if the hero is a dwarf, and be careful to spell the monster's name properly, especially if you are a Monk. It is usually safer to perform one or two "normal" genocides from the uncursed scroll of genocide and/or a throne: the master mind flayer can be generated via the summon nasties monster spell, which places them in melee range of the hero, and so should ideally be targeted first; regular mind flayers cannot be generated via the spell, unless they randomly replace an extinct or genocided nasty.

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

If master mind flayers are genocided, mind flayers can appear in their place if the summon nasties monster spell is cast.

Petkeeping and polyself

The traits that make (master) mind flayers fearsome enemies also make them powerful pets, though they are difficult and dangerous to tame—similarly, they are similarly very strong polymorph forms for the hero, due to their ability to eat brains among their other traits. Pet mind flayers can make quick work of shopkeepers and various tough monsters with the extra damage from brain-eating, though there are a few monsters that in turn pose a serious threat should a hero or pet (master) mind flayer attempt to eat their brain:

  • Shapeshifters may go down quickly, but a pet flayer will likely eat its corpse and polymorph.
  • Green slimes are extremely likely to turn a pet mind flayer into a slime, while a hero that lands an intelligence-drain attack on a green slime will suffer delayed sliming as if they had been hit with a sliming attack.
  • Cockatrices, chickatrices and Medusa will turn a mind flayer to stone if a tentacle attack lands, though a pet mind flayer will generally not attack a footrice. For the hero, this causes both instant stoning and delayed stoning if the former is stopped by life saving.
  • Jellies have passive attacks that can easily rack up enough damage to kill a hapless mind flayer attacking one. Ochre jellies are a common culprit, and it may be worth giving a pet flayer yellow dragon scales (or dragon scale mail) to provide acid resistance.
  • A mind flayer pet or hero attacking any of the Riders with brain-eating attacks will instantly die if the attack lands.
  • A mind flayer hero can become oversatiated from eating brains, with a significant risk of choking from eating anything afterward—this is an instadeath even while polymorphed.

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

Per commit 0891ef4e, monsters wearing alchemy smocks gain acid resistance from them in addition to poison resistance.

History

The intelligence drain damage type first appears with the mind flayer in NetHack 3.1.0.

Messages

Your brain is eaten! Your last thought fades away.
You were hit by a successful brain-eating attack when your base intelligence was already at 3.
Unfortunately your brain is still gone.
You died of brainlessness after an amulet of life saving revived you.
You feel like a scarecrow.
You are in explore or wizard mode, and you chose not to die of brainlessness.

Variants

Variants of NetHack may give other monsters intelligence-draining attacks, including the hero in some cases.

SLASH'EM

In SLASH'EM, lycanthrope heroes have a racial minimum intelligence of 1, while vampire heroes have a minimum intelligence of 0—this naturally means that it will be somewhat harder for heroes of these races to die from becoming brainless. Note that a base intelligence lower than 3 (which is not normally possible in NetHack) will be displayed as "3" regardless.

The migo queen has an intelligence-draining sting attack.

The ring of free action grants additional protection against the intelligence-draining tentacle attacks of (master) mind flayers: the chance is dependent on the hero's luck, ranging from a 12 chance at 0 luck to 910 at maximum luck.

The invulnerability granted from quaffing a potion of invulnerability does not prevent the hero from becoming brainless.

dNetHack

In dNetHack, several monsters have intelligence drain attacks:

  • Ancients of thought can drain intelligence with their "inhalation" attacks.
  • Elder brains and Daruth Xaxox have two intelligence drain attacks that can reach targets anywhere within a 5x5 square centered on the attacker's square.
  • Drow alienists have an intelligence drain attack that can reach targets anywhere within a 5x5 square centered on the attacker's square.
  • Migo philosophers and migo queens have intelligence-draining claw attacks.
  • Alhoons have a brain-eating tentacle attack.
  • Lugribossk has three brain-eating tentacle attacks.
  • Star spawn have a brain-eating tentacle attack and a second brain-eating attack that occurs if the hero has 40 or more insight. A star spawn's attacks ignore worn armor, meaning that helmets will not protect the hero or a monster from them.
  • Dream eaters have an intelligence-draining touch attack, while veil-renders have two intelligence-draining touch attacks.

notdNetHack

In notdNetHack, in addition to dNetHack details, all Illithanachronounbinders start the game with a tentacle attack that automatically occurs in melee, and works as brain-eating attacks do for the hero in NetHack.

Villithids have a brain-eating tentacle attack.

The Illithid Staff and The Elder Cerebral Fluid both inflict intelligence drain on hit should they be used against the hero.

The Crown of Berith is an artifact helmet that is treated as always greased, allowing it to always block brain-eating tentacle attacks while non-cursed.

EvilHack

In EvilHack, zombies are given brain-eating bites attacks that can also cause illness; alhoons have two brain-eating tentacle attacks, and neothelids have three brain-eating tentacle attacks per round.

Illithid heroes have a brain-eating attack that have a chance to occur during melee attacks, which grant nutrition when they occur if the target is not mindless or incorporeal. Draugr heroes are immune to brain-eating attacks by virtue of being undead, and as zombies can utilize brain-eating bite attacks of their own on 14 of melee attacks: these attacks inflict illness on non-resistant targets, grant the draugr nutrition if the target is not mindless or incorporeal, and may cause certain monsters to reanimate as corresponding zombies if the bite or the resulting sickness kills them. Brain-eating attacks from a draugr or illithid hero are suppressed automatically against hazardous targets such as black dragons.

Psychic resistance renders a hero or monster immune to intelligence loss from brain-eating attacks: illithid heroes start each game with psychic resistance, and all other illithids possess the property.

Hack'EM

In Hack'EM, tinfoil hats and plasteel helms protect against brain-eating attacks.

notnotdNetHack

In notnotdNetHack, in addition to notdNetHack details, life saving that occurs when a hero becomes brainless will reset the hero's intelligence to 5, as done when declining to die in explore mode or wizard mode.

References

  1. Jump up src/mhitu.c in NetHack 3.6.7, line 840
  2. Jump up src/mhitu.c in NetHack 3.6.7, line 1142
  3. Jump up src/mhitu.c in NetHack 3.6.7, line 845
  4. Jump up src/mhitu.c in NetHack 3.6.7, line 1149
  5. Jump up src/mhitu.c in NetHack 3.6.7, line 857
  6. Jump up src/mhitu.c in NetHack 3.6.7, line 1152
  7. Jump up src/mhitu.c in NetHack 3.6.7, line 1144
  8. Jump up src/mhitu.c in NetHack 3.6.7, line 1159
  9. Jump up to: 9.0 9.1 src/mhitu.c in NetHack 3.6.7, line 1164
  10. Jump up src/mhitu.c in NetHack 3.6.7, line 1170: calls eat_brains function in eat.c
  11. Jump up src/eat.c in NetHack 3.6.7, line 496: eat_brains function
  12. Jump up src/mhitu.c in NetHack 3.6.7, line 1174
  13. Jump up src/eat.c in NetHack 3.6.7, line 606
  14. Jump up to: 14.0 14.1 src/eat.c in NetHack 3.6.7, line 605
  15. Jump up src/eat.c in NetHack 3.6.7, line 505
  16. Jump up src/eat.c in NetHack 3.6.7, line 581
  17. Jump up src/mhitu.c in NetHack 3.6.7, line 1165
  18. Jump up to: 18.0 18.1 src/eat.c in NetHack 3.6.7, line 519
  19. Jump up src/eat.c in NetHack 3.6.7, line 532
  20. Jump up src/eat.c in NetHack 3.6.7, line 577
  21. Jump up src/eat.c in NetHack 3.6.7, line 582
  22. Jump up src/eat.c in NetHack 3.6.7, line 585
  23. Jump up src/mhitm.c in NetHack 3.6.7, line 1400
  24. Jump up src/mhitm.c in NetHack 3.6.7, line 1407
  25. Jump up src/mhitm.c in NetHack 3.6.7, line 1415
  26. Jump up src/eat.c in NetHack 3.6.7, line 503
  27. Jump up src/eat.c in NetHack 3.6.7, line 549
  28. Jump up src/eat.c in NetHack 3.6.7, line 613
  29. Jump up src/eat.c in NetHack 3.6.7, line 553
  30. Jump up src/eat.c in NetHack 3.6.7, line 617
  31. Jump up src/eat.c in NetHack 3.6.7, line 626
  32. Jump up src/eat.c in NetHack 3.6.7, line 561
  33. Jump up src/eat.c in NetHack 3.6.7, line 570
  34. Jump up src/eat.c in NetHack 3.6.7, line 575
  35. Jump up src/eat.c in NetHack 3.6.7, line 632