Difference between revisions of "Displacement"

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:''For pet displacement, see [[Pet#Speed|Pet § Speed]]''
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{{otheruses|the property|displacing pets by switching places|Pet#Speed}}
  
Displacement is a property granted by the [[cloak of displacement]]. Non-elven [[Ranger]]s start with a cloak of displacement (elves get an [[elven cloak]] instead).
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'''Displacement''' is a [[property]] in ''[[NetHack]]'' that causes your image to appear a tile or two away from where you actually are, which can misdirect the attacks of [[hostile]] [[monster]]s. The [[cloak of displacement]] is the only source of the property, and no monsters have intrinsic displacement.
  
== Effects ==
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{{upcoming|3.7.0|[[Displacer beast]]s have the displacement property, which is implemented similar to some of the variants listed below; fighting them may cause you to displace them instead of attacking, and force-fighting via {{kbd|F}} may similarly cause you to attack thin air. The [[corpse]] or [[tin]] of a displacer beast confers temporary intrinsic displacement when eaten.}}
'''Displacement''' causes your image to appear a tile or two away from where you actually are. This makes it very difficult for monsters to hit you. The [[cloak of displacement]], which is currently the only way this property can be obtained, is prized in the early game for it.
 
  
Displacement will make any given monster think you are at a random square within a 5×5 area centered on the player; in other words, the monster will think you are 0–2 squares away from where you are. If you do not have a clear line of sight to the monster, it will only generate the image in a 3×3 square around you. This is presumably to prevent monsters being alerted to your presence from well around corners, or from the other side of a closed door.
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==Description==
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A particular hostile monster will perceive a character with displacement as occupying a random square within a 5×5 area centered on them, i.e. they will think the character is 1 or 2 squares away from their actual location. This is reduced to a 3×3 area around the character if they do not have a clear line of sight to the monster, presumably to prevent monsters being alerted to their presence from well around corners or the other side of a closed door.
  
Shopkeepers and aligned priests are not fooled by displacement if you are generating [[conflict]], and they won't hesitate to attack you.  
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A monster that does not know the location of a character with displacement has a {{frac|4}} chance of discovering it during each of its turns, and a monster that learns the character's location is unaffected by their displacement until the character moves again, similar to [[invisibility]]. A monster fooled by a character's displaced image will often attack it instead, and may even move in the wrong direction entirely, with the odds of this varying widely depending on the character's surroundings and movement.<!--Old revision claimed a range of 0-28%, with odds "generally 8.7% in an open room if you're moving away from the monster"; citation + math check would be lovely.--> Shopkeepers and aligned priests are not fooled by displacement if you are generating [[conflict]], and they will not hesitate to attack you.  
  
As the observant reader will have figured out from the last paragraph, displacement is done per-monster, so your displaced image will generally be in two different locations for two different monsters. This means it is possible for one monster to see your image in the square of another monster. This will not cause the monsters to damage each other in melee&mdash;such attacks still produces the "wild miss" message&mdash;but they may still harm each other with breath weapons, ranged weapons, and the like.
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Displacement is done per-monster, so a character's displaced image will generally be in two different locations for two different monsters. This makes it possible for one monster to see the character's image in the square of another monster: monster melee attacks that target such a square will miss, but breath weapons, ranged weapons and the like will still deal damage.
  
If a monster knows where you are, displacement has no effect, unlike [[invisibility]] which still grants a &minus;2 to-hit bonus when a monster knows your location. However, when a monster does not know your location, it only has a {{frac|4}} chance per turn of figuring out where you actually are, as opposed to {{frac|3}} for invisibility. Like invisibility, each time you move, you must be "found" again by the monster in question. This makes having displacement or invisibility invaluable when you are running from a fight you are ill-equipped for.
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===Bribery===
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If a lawful [[demon prince]] teleports to demand a bribe from a character with displacement, they may warp next to their displaced image - this will cause them to become hostile without a chance of being pacified.
  
== Hazards ==
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==Strategy==
Assuming no better or additional sources of [[magic cancellation]], a cloak of displacement's MC1 means a higher chance that a monster's [[Magic cancellation#Mechanics|special attack]] succeeds if they do hit you.
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Displacement is invaluable when running from a fight that the character are ill-equipped for, especially in the early game. Non-[[Elf (starting race)|elven]] [[Ranger]]s notably start with a +2 cloak of displacement - elven rangers are given an [[elven cloak]] instead to counterbalance their better weapons.{{refsrc|src/u_init.c|200|nethack=3.6.7|comment=A comment explains "the weaker cloak for elven rangers is intentional--they shoot better"}}{{refsrc|src/u_init.c|211|nethack=3.6.7|comment=Elven substitutions for initial inventory}}
  
If a lawful [[demon prince]] ([[Asmodeus]] or [[Baalzebub]]) mistakenly demands a bribe from your displaced image, he will become hostile without a chance of being pacified.
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In terms of combat, invisibility is a property of somewhat similar use that applies a &minus;2 to-hit penalty to monsters that cannot see you, and tends to be far more common and accessible than displacement. Even if you are discovered, moving will cause them to lose track of your presence and attack the square you previously occupied; displacement does not affect monster awareness of your presence so much as their ability to pinpoint you. However, the odds of discovery are more likely for invisibility, with a {{frac|3}} chance during each of their turns compared to {{frac|4}} with displacement. Since both properties function on a per-monster-turn basis, fast monsters such as [[soldier ants]] are likely to find you quickly no matter which of them you use - invisibility will also override displacement if you have both properties, unless you are fighting monsters that can [[see invisible]]. On a somewhat lesser note, being invisible will cause [[shopkeeper]]s to block the entrances to their [[shop]] - they can also see invisible and will not be fooled by displacement if angered.
  
== Displacement vs invisibility ==
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In the long term, monsters that can see invisible become more common as you progress; fewer monsters are unaffected by displacement, and even demon lords and princes can be fooled by it, though beware of this if you intend to bribe the lawful ones!
For those trying to decide whether to use a cloak of displacement or invisibility, important points have been outlined below:
 
  
* Displacement is not [[invisibility]]. Unlike invisibility, displacement still allows monsters to see you, and cannot be used as a tool for sneaking past monsters.
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==Messages==
* Invisibility provides a &minus;2 to-hit bonus if your adversary cannot see invisible. This is equivalent to 2 points of AC without any damage reduction.
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{{message|You feel that monsters have difficulty pinpointing your location.|You put on a cloak of displacement. The cloak is identified.}}
* Invisible players will not be let into shops, but this is a minor inconvenience if the source of your invisibility is your cloak, as you may simply take it off.
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{{message|You feel that monsters no longer have difficulty pinpointing your location.|You removed a cloak of displacement. The cloak is identified.}}
* As noted above, your displaced image will not cause one monster to attack another in melee. This is most likely a result of the difficulties inherent in implementing a "hostile state" between two monsters, the equivalent to "It gets angry!" for the player.
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{{message|<[[Foo]]> strikes at your <invisible> displaced image and misses you!|A monster attacked a spot where they believed you to be as a result of displacement; "invisible" is appended if you are invisible and the monster can see invisible.}}
* Moving while invisible will cause monsters to attack the square you once occupied. Displacement generates your image somewhere within two squares to either side, meaning there is a very small chance of the monster moving in the wrong direction entirely. This chance is, however, very small: from 0% to 28%, depending on your surroundings and movement, but it will generally be 8.7% in an open room if you're moving away from the monster; which you probably are if you're hoping it will run away from you.
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{{message|<Foo> smiles <engagingly/seductively> at your <invisible> displaced image...|As above, but you were targeted with a seduction attack.}}
* While invisible, each turn, a given monster will have a 1 in 3 chance of discovering your position. With displacement, this chance is only 1 in 4 (non-stacking), making it easier to survive when fleeing. This "chance of discovery" is per ''monster'' turn, so fast monsters like soldier ants will find you a lot faster no matter which you are using.
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{{message|The invisible <foo> whispers at thin air.|A demon lord or prince attempted to demand a bribe from you, but was fooled by your displaced image - this will immediately turn them hostile.}}
* Plenty of things can see invisible; very few can see through displacement.
 
* There are many ways to become invisible ([[cloak of invisibility]], [[spellbook of invisibility]], [[ring of invisibility]], [[potion of invisibility]], [[wand of make invisible]], and [[stalker]] meat), whereas displacement may only be gained with the cloak.
 
 
 
In summary, the biggest advantage of invisibility ''and'' displacement are the 66% and 75% chances respectively that a monster will not know where you are if you have moved. For this reason, displacement and invisibility are quite evenly matched. However, the other advantages, like the to-hit penalty for invisibility, are trivial. Furthermore, if you have both displacement and invisibility, invisibility's lesser stay-hidden chance of 66% will be used instead of displacement's 75%, and invisibility will nullify the effects of displacement. Therefore, having both displacement and invisibility simultaneously is ''just invisibility'' unless you are fighting monsters that can [[see invisible#Monsters with intrinsic see invisible|see invisible]].
 
  
 
==Variants==
 
==Variants==
Generally speaking, in variants, the cloak grants [[MC]]2 instead of MC1, being based on NetHack 3.4.3.
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Some variants implement a form of monster displacement: among those, a few also grant it to two [[Deferred feature|deferred monsters]] within the code - the shimmering dragon, whose scales are intended to confirm displacement, and its baby form.
  
 
===SLASH'EM===
 
===SLASH'EM===
 
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In [[SLASH'EM]], monster displacement exists, with [[displacer beast]]s possessing the property intrinsically. Shimmering dragons and their babies instead have a much lower [[AC]] than other dragons, simulating "displacement" by making them harder to hit.
In [[SLASH'EM]], monster displacement exists. Therefore, monsters can be displaced, resulting in amusing remarks such as
 
; "You displace the displacer beast."
 
Only displacer beasts have displacement; (baby) shimmering dragons, whose scales give displacement, merely have a much lower [[AC]] than other dragons, making them harder to hit (thus simulating "displacement").
 
  
 
===GruntHack===
 
===GruntHack===
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[[GruntHack]] implements proper displacement for monsters: Monsters can appear in a different location from where they actually are, including inside walls, or on another monster's square. [[Telepathy]] or [[monster detection]] will reveal their actual location, making it possible for the displaced monster's glyph to show up on two different squares. Trying to walk onto a displaced monster's square will not attack it.
  
GruntHack implements proper displacement for monsters. Monsters can appear in a different location from where they actually are, including inside walls, or on another monster's location. Only vision is fooled by displacement&mdash;telepathy or monster detection will see the true location. This means that if you can see the monster both ways, you see the monster in 2 locations. Trying to walk onto a displaced monster will not attack it. [[Dragon (GruntHack)|Adult shimmering dragons]] have intrinsic displacement, and their scales confer displacement.
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[[Shimmering dragon (GruntHack)|Adult shimmering dragons]] have intrinsic displacement, and their scales confer displacement.
  
 
===FIQHack===
 
===FIQHack===
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[[FIQHack]] implements monster displacement that is somewhat similar to GruntHack, with the following differences:
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* If a character can sense the monster with telepathy, monster detection or similar, the displaced image will never be shown. A character that cannot see the displaced image, but is able to see the square where their true location is, will see the monster's true location as normal.
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* The displaced image will never appear on a square the monster cannot normally inhabit (e.g. inside walls).
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* A character moving onto a square where a monster's displaced image is will try to attack that square, including other monsters that happen to occupy the square, and the same is true of monsters attacking a displaced image in a square occupied by another monster.
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Shimmering dragons, their baby forms and their scales are also present - unlike in GruntHack, baby shimmering dragons have intrinsic displacement as well as adults.
  
In '''FIQHack''', the cloak of displacement provides MC3 instead of MC2.
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===xNetHack===
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In [[xNetHack]], displacer beasts have the displacement property, which is implemented similar to some other variants: fighting them may cause the character to displace them instead of attacking, and force-fighting via {{kbd|F}} may similarly cause them to attack thin air. The [[corpse]] or [[tin]] of a displacer beast confers temporary intrinsic displacement when eaten.
  
In addition, FIQHack implements monster displacement. It works somewhat similar to in GruntHack with the following differences:
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===EvilHack===
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In [[EvilHack]], monsters can gain displacement from the same sources as the player character, and monster displacement functions somewhat similarly to xNetHack and GruntHack. A message is also printed if the monster discovers a displaced character's actual location.
  
* If you can sense the monster with telepathy, monster detection or similar, the displaced image will never be shown, avoiding showing 2 images in that case.
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====Messages====
* The displaced image will never appear in a spot the monster couldn't normally be on (such as inside walls).
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{{message|Your displaced image doesn't fool <the monster>!|A monster figured out your actual location while you had displacement.}}
* If you can't see the displaced image, but would be able to see the true location, you will see the monster's true location.
 
* You will (try to) attack displaced images if moving onto them. If there is another monster there, you will attack it. The same thing now happens if a monster tries to attack your (or another monster's) displaced image that is on another monster.
 
* Unlike in GruntHack, baby shimmering dragons also have intrinsic displacement.
 
  
== Origin ==
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==References==
In ''[[Dungeons & Dragons]]'', a '''displacer beast''' appears several feet away from where it truly stands.
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<references/>
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{{nethack-367}}
 
[[Category:Properties]]
 
[[Category:Properties]]
{{nethack-343}}
 

Latest revision as of 16:12, 22 April 2024

This article is about the property. For displacing pets by switching places, see Pet#Speed.

Displacement is a property in NetHack that causes your image to appear a tile or two away from where you actually are, which can misdirect the attacks of hostile monsters. The cloak of displacement is the only source of the property, and no monsters have intrinsic displacement.

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

Displacer beasts have the displacement property, which is implemented similar to some of the variants listed below; fighting them may cause you to displace them instead of attacking, and force-fighting via F may similarly cause you to attack thin air. The corpse or tin of a displacer beast confers temporary intrinsic displacement when eaten.

Description

A particular hostile monster will perceive a character with displacement as occupying a random square within a 5×5 area centered on them, i.e. they will think the character is 1 or 2 squares away from their actual location. This is reduced to a 3×3 area around the character if they do not have a clear line of sight to the monster, presumably to prevent monsters being alerted to their presence from well around corners or the other side of a closed door.

A monster that does not know the location of a character with displacement has a 14 chance of discovering it during each of its turns, and a monster that learns the character's location is unaffected by their displacement until the character moves again, similar to invisibility. A monster fooled by a character's displaced image will often attack it instead, and may even move in the wrong direction entirely, with the odds of this varying widely depending on the character's surroundings and movement. Shopkeepers and aligned priests are not fooled by displacement if you are generating conflict, and they will not hesitate to attack you.

Displacement is done per-monster, so a character's displaced image will generally be in two different locations for two different monsters. This makes it possible for one monster to see the character's image in the square of another monster: monster melee attacks that target such a square will miss, but breath weapons, ranged weapons and the like will still deal damage.

Bribery

If a lawful demon prince teleports to demand a bribe from a character with displacement, they may warp next to their displaced image - this will cause them to become hostile without a chance of being pacified.

Strategy

Displacement is invaluable when running from a fight that the character are ill-equipped for, especially in the early game. Non-elven Rangers notably start with a +2 cloak of displacement - elven rangers are given an elven cloak instead to counterbalance their better weapons.[1][2]

In terms of combat, invisibility is a property of somewhat similar use that applies a −2 to-hit penalty to monsters that cannot see you, and tends to be far more common and accessible than displacement. Even if you are discovered, moving will cause them to lose track of your presence and attack the square you previously occupied; displacement does not affect monster awareness of your presence so much as their ability to pinpoint you. However, the odds of discovery are more likely for invisibility, with a 13 chance during each of their turns compared to 14 with displacement. Since both properties function on a per-monster-turn basis, fast monsters such as soldier ants are likely to find you quickly no matter which of them you use - invisibility will also override displacement if you have both properties, unless you are fighting monsters that can see invisible. On a somewhat lesser note, being invisible will cause shopkeepers to block the entrances to their shop - they can also see invisible and will not be fooled by displacement if angered.

In the long term, monsters that can see invisible become more common as you progress; fewer monsters are unaffected by displacement, and even demon lords and princes can be fooled by it, though beware of this if you intend to bribe the lawful ones!

Messages

You feel that monsters have difficulty pinpointing your location.
You put on a cloak of displacement. The cloak is identified.
You feel that monsters no longer have difficulty pinpointing your location.
You removed a cloak of displacement. The cloak is identified.
<Foo> strikes at your <invisible> displaced image and misses you!
A monster attacked a spot where they believed you to be as a result of displacement; "invisible" is appended if you are invisible and the monster can see invisible.
<Foo> smiles <engagingly/seductively> at your <invisible> displaced image...
As above, but you were targeted with a seduction attack.
The invisible <foo> whispers at thin air.
A demon lord or prince attempted to demand a bribe from you, but was fooled by your displaced image - this will immediately turn them hostile.

Variants

Some variants implement a form of monster displacement: among those, a few also grant it to two deferred monsters within the code - the shimmering dragon, whose scales are intended to confirm displacement, and its baby form.

SLASH'EM

In SLASH'EM, monster displacement exists, with displacer beasts possessing the property intrinsically. Shimmering dragons and their babies instead have a much lower AC than other dragons, simulating "displacement" by making them harder to hit.

GruntHack

GruntHack implements proper displacement for monsters: Monsters can appear in a different location from where they actually are, including inside walls, or on another monster's square. Telepathy or monster detection will reveal their actual location, making it possible for the displaced monster's glyph to show up on two different squares. Trying to walk onto a displaced monster's square will not attack it.

Adult shimmering dragons have intrinsic displacement, and their scales confer displacement.

FIQHack

FIQHack implements monster displacement that is somewhat similar to GruntHack, with the following differences:

  • If a character can sense the monster with telepathy, monster detection or similar, the displaced image will never be shown. A character that cannot see the displaced image, but is able to see the square where their true location is, will see the monster's true location as normal.
  • The displaced image will never appear on a square the monster cannot normally inhabit (e.g. inside walls).
  • A character moving onto a square where a monster's displaced image is will try to attack that square, including other monsters that happen to occupy the square, and the same is true of monsters attacking a displaced image in a square occupied by another monster.

Shimmering dragons, their baby forms and their scales are also present - unlike in GruntHack, baby shimmering dragons have intrinsic displacement as well as adults.

xNetHack

In xNetHack, displacer beasts have the displacement property, which is implemented similar to some other variants: fighting them may cause the character to displace them instead of attacking, and force-fighting via F may similarly cause them to attack thin air. The corpse or tin of a displacer beast confers temporary intrinsic displacement when eaten.

EvilHack

In EvilHack, monsters can gain displacement from the same sources as the player character, and monster displacement functions somewhat similarly to xNetHack and GruntHack. A message is also printed if the monster discovers a displaced character's actual location.

Messages

Your displaced image doesn't fool <the monster>!
A monster figured out your actual location while you had displacement.

References

  1. src/u_init.c in NetHack 3.6.7, line 200: A comment explains "the weaker cloak for elven rangers is intentional--they shoot better"
  2. src/u_init.c in NetHack 3.6.7, line 211: Elven substitutions for initial inventory