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In NetHack, polymorph refers to the magic that changes one creature into a different species, or changes an object to another object of the same type. Shapeshifters and werecreatures have similar, but slightly different abilities.

This article deals mainly with monster- or self-polymorph. The practice of polymorphing objects is also known as polypiling, and is explained in the article behind that link.

Polymorph is one of the more complex aspects of NetHack. It can be a great danger if not done under the control of the player, but a prepared player can use it to gain many benefits. If you are transformed unexpectedly, you may turn into a weaker monster or die instantly; your valuable armor may also be destroyed. A weak enemy may unexpectedly turn into a dangerous one. On the other hand, you can deliberately turn into a much stronger monster, or a monster with useful abilities. Weak pets can be changed into powerful ones. You can also polymorph surplus items into more useful equipment.


You can aim a wand or spell of polymorph can be aimed at monsters or piles of items on the floor. Aiming downwards using > polymorphs the objects on your square; aiming upwards using < has no effect; and aiming at yourself using . will naturally polymorph you. Dipping an object into a potion of polymorph will polymorph it.

Other sources of polymorph do not apply to objects:

  • Wearing a ring of polymorph will polymorph you from time to time. It can be eaten for a 13 chance of acquiring the intrinsic.
  • Stepping into a polymorph trap will polymorph you or a monster. The trap disappears after you use it once, but monsters can use it indefinitely.
  • Quaffing a potion of polymorph will polymorph you or a monster.
    • Getting hit by this potion. Thankfully, monsters will not do this to you; only you can do this to them. Vapors will not polymorph you (good for use-testing).
  • Quaffing from a sink produces toxic wastes, or randomly dispenses potion of polymorph; both effects will polymorph you.
  • Eating the corpse of a chameleon or doppelganger, or digesting a sandestin.
  • Becoming afflicted with lycanthropy, and thus polymorphing into a werecreature from time to time.

The inventory of a polymorphed monster is not polymorphed, but worn armor can be destroyed or temporarily absorbed. Magic resistance blocks the effect of all "involuntary" polymorphs; this means that it will not protect from a ring of polymorph, which is considered to be worn voluntarily. A monster's MR will protect it against polymorph traps.

If you polymorph into a form that is not the same as your starting race, you break the polyselfless conduct. ("Changing" into your original race is not a polymorph, strictly speaking, and this article calls it "Polymorphing into your own race".) Polymorphing any object breaks the polypileless conduct.

Effects of polymorph

For effects specific to yourself, see #Self-polymorph.

Restrictions on polymorphing

Certain monsters are off-limits to polymorph,[1] either by you or a monster; these include:

System shock

If you polymorph without polymorph control and it is not a special case, there is a 19 − Con20 chance that it will fail, and you will instead suffer 1d30 damage and abuse constitution: "You shudder for a moment." This is called system shock. Monsters and pets can also be affected by the wand, potion, or spell of polymorph, with a fixed chance of 125 after factoring in resistance. If the monster is affected, it will die instantly and not leave a corpse.


See also: Physical size

When a creature is wearing any torso armor (body armor, shirt, or cloak), and becomes something Large or bigger, a non-humanoid Medium or bigger, or a winged gargoyle or marilith (wings and extra arms don't fit), the armor will burst apart. (If you polymorph into a large whirly monster, the armor is not destroyed.) When this happens to a monster, you hear a "ripping" or "cracking" sound, which warns you that a polymorph trap or shapeshifter may be present on the level.

If you are wearing dragon scales or dragon scale mail and are polymorphed without polymorph control, you will turn into a dragon of the appropriate color and merge with your scales; shirts and cloaks are still destroyed. See Dragon scale mail § Polymorph.

When a creature becomes too small for its armor, the armor falls to the floor, also creating a distinctive noise ("a clank" or "a thud"). Monsters of size Small will shrink out of torso armor; Tiny monsters also shrink out of boots, gloves, shields and helms (they can wear no armor). Handless monsters will drop gloves and shields. Horned monsters will drop helmets. Non-humanoid monsters, or monsters without suitable body parts, also cannot wear certain types of armor.

Other equipment

Monsters can always wear rings and amulets, although some may be physically unable to remove equipped items or put on additional ones in their new form.

If you were wielding an object and your new form has no hands, you will drop it.

Polymorphing causes you to retouch all your inventory items,[2] potentially causing artifact blasts or silver damage.


Main article: Encumbrance

Smaller or more light-weight monsters cannot carry as much as larger ones. Non-humanoid monsters have especially limited capacity. When you are unexpectedly polymorphed into one, you may have to drop nearly all of your items before you can do anything useful.

Your carrying capacity is scaled by your form's corpse weight (or size if it leaves no corpse), and is affected by the monster "strong" attribute. See that article for the details.


Shapeshifters and werecreatures have innate polymorph ability and will change to a different form from time to time. You can prevent them from doing this by wearing a ring of protection from shape changers. Other than that, a polymorphed monster or object stays in its new form permanently.

If a monster is fleeing, it may use a potion or wand of polymorph, or an adjacent polymorph trap in a desperate move. A monster may also inadvertently step onto the trap. If it becomes a much more powerful monster, such as an arch-lich, this can lead to YAAD.

When a monster polymorphs, the change is permanent. For example, if you change your dog into a dragon, it will never become a dog again (except by chance in a subsequent polymorph).

If you have lycanthropy, you will sometimes polymorph into a creature (a jackal, for example). There is also a monster in the game called a werejackal, which changes occasionally from its human form into a jackal. The similarity ends when you or the monster lose all HP in jackal form. You will become your normal race again, while the werejackal will die without transforming back into a human.

Polymorphing monsters

Since polymorphing a monster has unpredictable results, this tactic is only feasible for very powerful monsters, as they have a good chance of becoming a weaker one. Monsters with high experience level and monster MR may resist polymorphing, so this is not a reliable method to escape impending death. For example, the Riders cannot be polymorphed at level 30. An arch-lich at level 25 will resist 85% of the time if you are level 30 and attempt to polymorph it with a spell; it can never be polymorphed with a wand.

Lawful and neutral characters may wish to polymorph humans such as shopkeepers and aligned priests before killing them, to avoid the penalties for murder.


Your starting pet will only go so far: cats and dogs reach a normal maximum of level 9 and 72 HP, for example. But you can get more out of it by polymorphing it.

Since you cannot control the outcome of a pet's polymorph, the best way to do this is to use a polymorph trap repeatedly until you get a satisfactory result. The trap is never used up by pets and other monsters. If you have magic resistance, you can step onto the trap and then displace your pet onto it. You can also step next to the trap and use a magic whistle until your pet happens to land on the trap. You can also leash your pet and stand next to the trap; it does not want to step onto the trap, but it eventually will. You can also read a scroll of earth, push the boulders around the trap, and then displace your pet onto the trap. If you have many charges in a wand of polymorph, or are able to cast the spell, those are viable alternatives (but beware of system shock, as it will count as you having killed the pet!) Less workable methods are finding chameleon or doppelganger corpses for it to eat, or breaking a potion of polymorph on its body.

Displacing your pet onto a trap decreases its tameness by one point. Be wary about displacing pets that have already become somewhat powerful monsters. Pets, like other monsters, can suffer a system shock if you are using the spell, wand, or potion. If the pet experiences a system shock, you will suffer the usual penalties for killing your pet.

Once your pet turns into a gray dragon or its baby form, it acquires intrinsic magic resistance and will be immune to all forms of polymorph, except from eating corpses. If it acquires a high level and monster MR, such as if it turns into an arch-lich, it may also become immune. If you do not have a magic whistle or magic resistance to displace your pet, then sessile pets will not polymorph any further. Finally, if you get a shapeshifter and do not have a ring of protection from shape changers, then it will only shapeshift on the trap. Otherwise, you can keep trying. See Pet § Preferred pets for pets that many players find useful.

You can also gain new pets by polymorphing into an oviparous creature and laying eggs.


Having polymorph control allows you to specify what to polymorph yourself into, unless you are unconscious or stunned. This is subject to the game restrictions. For strategy, see Polymorph control § Strategy.

An amulet of unchanging blocks polymorph completely, but a ring of protection from shape changers will not. If you are in the form of a metallivore and can eat amulets, eating one may also return you to your original form.

Polymorphing into other monsters

There are a few special cases when polymorphing in an uncontrolled manner:

If, while wearing dragon scales or a dragon scale mail, you are polymorphed into a dragon of the same color, the dragon scales will be merged into your skin.

Changing back

Polymorphing yourself is never permanent, unless you polymorph into your own race (see § Polymorphing into your own race). Otherwise, you will stay in monster form for 499+1d500 turns.[4] If your new monster form has a higher experience level than you, the timeout is scaled down in proportion to the levels.[5]. To be precise, the polymorph duration will be multiplied by

\frac {player XL} {monster XL}.

E.g., if a XL 2 player polymorphs into a master mind flayer (XL 13), the duration will be at most 153 turns:

999 * \frac {2}{13}

If the timeout ends but you are wearing an amulet of unchanging, between 1 and (1 + 100 × mlevel) turns are added to the timeout. mlevel refers to the monster form's experience level. Eating a mimic or stepping on a polytrap while magic resistant or unchanging have no effect on the timeout.

If you are killed in your new form because your HP became zero, you will change back: "You return to <race> form!" You will return to your original form with the HP and Pw you had before you polymorphed. However, if you are wearing an amulet of unchanging or are killed in any other way, such as stoning, sickness, hunger, choking, or a touch of death, you will immediately die. Being beheaded by Vorpal Blade or bisected by the Tsurugi of Muramasa are considered deaths by HP loss and return you to original form.

You can return to your normal form due to HP loss even when wearing an amulet of life saving, and it is not used up. However, it will protect you from system shock.

If you are polymorphed into a problematic form, you can zap a wand at yourself or throw an object upwards < so that it hits you, causing you to lose HP and change back. If you have no hands, a prayer to your god may change you back as well. If a monster is attacking you and reducing your HP, these measures may be unnecessary.

Another way to change back is to polymorph into your own race.

Being a gray dragon gives you magic resistance, so you cannot change back by looking for another polymorph trap.

If you genocide your original race or your role while polymorphed, "You feel dead inside." If you subsequently return to that form, you will die, even if wearing an amulet of life saving: "Unfortunately, you are still genocided..." If you quit before you return to your base form, the game-end message will be "quit while already on Charon's boat".

Attributes, intrinsics, and other stats

A user has suggested improving this page or section as follows:

"Please update: confirm 1 point drop in maximum power when unpolymorphing and whether it also applies to lycanthropy."

Your new HP is determined by the monster form's base level. This level is displayed instead of your experience level in the status bar, eg. HD: 13 for a master mind flayer. Your "real" level can be determined from spell failure rates (e.g. for the quest). Any change in current or maximum HP is temporary. Your Pw persists between forms.

Your strength, dexterity, constitution, intelligence, and charisma (but not wisdom) are saved when you polymorph to a monster, and restored when you get back to your old form, no matter what happened when you were polymorphed. For instance, if you had strength 16 and polymorphed to a dragon, your strength will be 18/**. If you eat a poisonous killer bee corpse, your strength may be reduced to 18/97, but after returning to an old form, your strength will again be 16.

Things are different with intrinsics. As a monster you will enjoy all intrinsics which you had before you polymorphed, all intrinsics of your new species, and all extrinsics acquired by magic items which you are wearing or wielding. You may acquire new intrinsics, and they will stay with you after returning to your old form. Therefore, if you became a dragon, it is a good idea to eat killer bees: the poison resistance which you obtain will stay with you, while the decline in your strength will not.

Hunger is not affected by polymorphing or returning back, only by polymorphing into your own race.

Amulets of change, if worn when polymorphed, change both your sex as your polymorphed form (if there are both male and female monsters of this kind) and your base form sex.

Players polymorphed into a jabberwock, adult dragon, raven, or crocodile will not stone monsters with a wielded cockatrice corpse.[6]

Polymorphing into your own race

Polymorphing into your own race is a special case. It does not break polyselfless conduct. Instead of being temporarily changed to a monster, you see the message "You feel like a new <race>!" and your character is randomly and permanently changed:

  • It adjusts your experience level by −2 to +2 levels.[7]
    • If the new level is higher than 30, it becomes 30.
    • If the new level is lower than 1, you die ("Your new form doesn't seem healthy enough to survive.") If saved by an amulet of life saving, you restore your old experience level.
    • If the new level is lower than the old one, it cannot be cured by a blessed potion of full healing.
    • Your innate properties, resistances, and skill slots are adjusted to match your new level.
  • Your strength, dexterity, constitution, and charisma change by −2 to +2 points (attrib.c).
  • Your maximum HP and energy are readjusted according to your new level and attributes in the following manner:[8]
    • First, all HP and energy gained by leveling is removed. (The game stores these values whenever you level.)
    • Then, the remainder is randomly multiplied by one of (80%, 90%, 100%, 110%), separately rolled for HP and energy.
      • The result is set equal to the new level if it ends up lower.
    • Then your HP and energy are increased as if you'd leveled to your new level from 1, taking in account your current constitution and wisdom bonuses.
    • Finally, your current HP and energy are adjusted proportionally to the change of maximum HP and energy.
  • You have a 110 chance of changing gender.
  • It sets your nutrition to a random value from 500 to 999.[9]
  • It cures both illness and food poisoning.[10]
  • It cures stoning, if you had been stiffening.
  • It technically cures sliming, but slime remains on your body; thus, the sliming process restarts and you have 10 turns to live.[11]
  • If your current HP is now 0 or negative, but you have polymorph control, it becomes 1 instead.
  • If your current HP is now 0 or negative, and you do not have polymorph control, you die.

It does not cure blindness, nor does it remove any of your intrinsics unless they were given by experience levels that you lost.

This process has curing effects, but for healthy adventurers, the DevTeam seems to have intentionally designed this function so that there is an equal chance that each adjustment is beneficial or harmful. As xanthian explains to rgrn, the expected value of the level change is zero. Because this function does not call rnl, your luck has no effect here. You also cannot use a unicorn horn or other such cure to regain any lost levels or attributes. A comment[12] explains how the source code adjusts your peak level to prevent this. The redist_attr function sets both your current and peak attributes, too. The becoming of a new "man" many times is thus no way to raise your experience level or your attributes. Performing it once after maximizing your constitution and wisdom may yield a maximum HP and energy boost, though, since the level-up bonuses were likely originally obtained with lower attributes.

In 3.4.3

Prior to NetHack 3.6.0, HP and energy changed differently: they were grown or shrunk in direct proportion to your level change, then a further adjustment of −9 to +9 points was applied.[13] It was consequently possible to bias the changes deliberately. At a very low experience level, polymorph has an equal chance of raising your level, or decreasing it and killing you. By cheating death with an amulet of life saving, one could accumulate the effects of gaining levels, which multiplied hit points and power. This was known as the polyself bug.

Other special cases

Polymorphing to your own race while being a monster just returns you to your basic form and then makes you "a new <race>" as in the previous section.

Polymorphing to a monster while already being monster is equivalent to returning to your human form and immediately polymorphing to the target monster. If you polymorph to a monster while already the same species, you see the message "You feel like a new <species>!"



In SLASH'EM, the attack of a genetic engineer can polymorph the player character and other monsters, and the #youpoly extended command allows controlled polymorphing at will for races and roles with that ability. Polymorph itself functions in a considerably different manner, detailed below.

Most monster and item polymorphs are temporary: Polymorphed items revert back to their original form after 500–999 turns, and polymorphed monsters revert back to their original form after 1000–1999 turns.[14][15] For monsters, temporary polymorphs can be made permanent by stoning the monster, then re-animating them with the spell of stone to flesh; eating the corpse of a chameleon or doppelganger, or digesting a sandestin, will still be permanent.

Items that are polymorphed are sometimes described as "hazy", e.g. when polymorphed using a potion of polymorph - in wizard mode, they will also appear as "hazy", e.g. "a hazy key". Polymorphed items function as the normal item would otherwise for the duration of their polymorph, and can be "fixed" permanently in their current form by dipping them in a potion of restore ability. This makes polypiling of rings, wands, and equipment much less effective and even potentially dangerous (e.g. a character wearing a hazy amulet of life saving that used to be an amulet of strangulation) unless they have several potions to spare for "fixing" items.

Killing a polymorphed monster causes them to revert to their original form with reduced HP: this makes dangerous enemies much harder to kill by polymorphing them into a weaker form, and it is also much harder to permanently upgrade a pet with polymorph. Polymorphing shopkeepers is no longer a reliable means of killing them either, though this can still disable, immobilize, or slow them enough for a character to rob the store or else turn them to stone. Hostile shapeshifters such as chameleons and lycanthropes become especially difficult: if killed while outside of base form, they can often shapechange again before a character can deal the finishing blow - conversely, a luckier character may be able to lower their HP enough that they undergo system shock and die as normal when trying to turn back.

When a character is polymorphed, if they become an intelligent monster with an attack that requires direct contact (biting, tentacles, etc), they will not use this attack against petrifying monsters, as opposed to using it and being instantly stoned - attacking bare-handed will still turn them to stone, however. If melee damage returns a character to normal form, they have a 13 chance of losing current and maximum HP equal to that form's monster difficulty, and the damage always occurs if the polymorph was controlled.[16]


xNetHack includes a polyinit option, which allows you to play the game permanently polymorphed into any monster except for unique monsters and player monsters. Besides those, this option allows forms that are normally inaccessible, such as an Archon or shade, though the game may be unstable in this state. This is a non-scoring game mode.


The rule chances for polymorph in SLASH'EM are still applicable in SlashTHEM, though temporarily polymorphed objects will appear as "hazy" in normal play.


  1. mondata.h in NetHack 3.4.3, line 77: See also monst.c, which lists the monsters to which this applies.
  2. polyself.c in NetHack 3.6.1, line 839
  3. polyself.c in NetHack 3.6.1, line 530
  4. polyself.c in NetHack 3.4.3, line 396
  5. polyself.c in NetHack 3.4.3, line 452
  6. The exact condition for stoning a monster with a wielded cockatrice corpse seems to be: (in natural form or (hit with weapon attack or hit with claw attack in slot 1 or hit with claw attack in slot 2 as a foocubus or hit with any attack in slot 1 as any L)). This also excludes the invalid polyforms Ixoth, Demogorgon, and Chromatic Dragon.
  7. polyself.c in NetHack 3.4.3, line 138
  8. src/polyself.c in NetHack 3.6.0, line 292
  9. polyself.c in NetHack 3.4.3, line 188
  10. polyself.c in NetHack 3.4.3, line 190: This calls make_sick in potion.c with SICK_ALL
  11. polyself.c in NetHack 3.4.3, line 210
  12. polyself.c in NetHack 3.4.3, line 144
  13. polyself.c in NetHack 3.4.3, line 169
  14. timeout.c in SLASH'EM 0.0.7E7F2, line 455
  15. timeout.c in SLASH'EM 0.0.7E7F2, line 590
  16. mhitu.c in SLASH'EM 0.0.7E7F2, line 2555

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