Polymorph refers to the magic that changes one creature into a different species, or changes an object to another object of the same type. A polymorph that affects you or a monster does not polymorph items carried in your or its inventory, although see below for effects on armor. Shapeshifters have a similar but slightly different power.

Several things can polymorph you, monsters, or objects:

  • ring of polymorph will polymorph you from time to time
  • spellbook of polymorph will polymorph you, monsters, or objects
  • wand of polymorph will polymorph you, monsters, or objects. Hostile monsters may zap it at themselves; a gnome suddenly turning into a master mind flayer when you are a level 3 character is quite unfortunate. Zapping your wand of polymorph at your pet and changing your little dog into a black dragon or a minotaur can be quite interesting. Zapping a wand of polymorph, or casting a spell of polymorph, at yourself or a monster will not affect your or the monster's inventory.
  • polymorph trap will polymorph you or monsters. Hostile monsters deliberately step into it once. Magic resistance protects against it.
  • potion of polymorph will polymorph you (if you quaff it), a monster (if you throw it at a monster; this also angers a peaceful monster), or an object (if you dip an object into the potion of polymorph).
  • eating the corpse of a chameleon or a doppelganger will cause you to polymorph.
  • eating or being bitten by a werecreature will polymorph you from time to time into that creature's beast form. This can be cured by prayer, quaffing holy water, or eating a sprig of wolfsbane.
  • drinking toxic waste from a sink

Polypiling is the practice of aiming polymorph at a pile of junk, hoping to produce better or rare items.
Polymerge combines stacks of items into golems.

When a creature is wearing body armor, a shirt and/or a 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. When this happens to a monster, a distinctive sound results, which may warn you that a polymorph trap is present on the level. When a creature becomes too small for its armor, the armor falls to the floor, also creating a distinctive noise. An exception is when you are wearing a dragon scales or mail (such as silver dragon scale mail) and get polymorphed into a dragon (in this case, a silver dragon) where your armor will "merge" with the dragon and not be destroyed, though the cloak and shirt will still be.


When you are polymorphed, it is always temporary, unless you're wearing an amulet of unchanging; you will eventually return to your old form as the polymorph times out. If your HP reaches zero while polymorphed, you will also return to your old form instead of dying. Being polymorphed will only "protect" you from death caused by HP loss. Dying in any way that does not reduce your HP, such as stoning, sliming, sickness, and the touch of death will kill you, rather than revert you to your original form. If you still have hands, a quick way out of an undesirable morph is to throw (non-weapon) objects up < until you "die".

If you have polymorph control, from wearing a ring of polymorph control or having eaten one and absorbed its intrinsic, you get to choose which monster to become.

If you are wearing dragon scales or dragon scale mail, you turn into that color dragon instead of a random monster, although wearing gray dragon scale mail will prevent a polymorph trap from affecting you by conferring magic resistance.

Unchanging (from an amulet of unchanging) completely prevents all polymorphs. If you are polymorphed already, it prevents you from returning to your old form.

You initially stay in monster form for 499+1d500 turns.[1] If your new monster form has a higher experience level than you, the timeout is scaled down in proportion to the levels, e.g. if you are level 7 and polymorph into a demilich (level 14), then you will stay as a demilich for 7/14 = half the normal time.[2] If an amulet of unchanging prevents you reverting when the morph times out, 1d(1+100*mlevel) turns are tacked on instead.[3] Mlevel here means your current monster form's experience level. Eating a mimic or stepping on a polytrap while magic resistant or unchanging have no effect on the timeout.

Uncontrolled polymorphs, such as caused by a surprise polymorph trap, have a (19-Con)/20 chance of causing a system shock, which results in d30 damage and exercise your constitution. You might also polymorph to your own race and die of level drain if applicable, see below.

If you genocide your base species while polymorphed, you will "feel dead inside". If you subsequently return to that form, you will die, even if you are wearing an amulet of life saving. If you quit before you return to your base form, the death message will be "quit while already on Charon's boat".

There are various strategic uses of self-polymorph. One can become a monster with higher base speed, a monster immune to stoning, a monster able to eat amulets and/or rings in order to absorb intrinsics, or a monster with a useful monster power. Monster powers include a were-creature's ability to summon pets, laying eggs which hatch into pets (only if the polyform is female), a spider's ability to spin webs, and many others. Disadvantages to polyself include losing the use of one's hands, losing the ability to wear armor, and losing encumbrance capacity.

One use of the self-polymorph would be turn yourself into a dragon, especially early on. Laying an egg in order to get a baby silver or gray dragon as a pet can help you to defeat otherwise difficult monsters for higher levels. If you lay several eggs, grow all the baby dragons into adult, and get them killed (for an early character, the best method is either conflict or untaming some of them and having the tame dragons defeat the untamed ones) then you have a good chance of getting dragon scales for creating dragon scale mail.

If you are self-polymorphed into a brown pudding and split, the clones will remain after you return to your normal form, and their names will be the same as your name.

Attributes, intrinsics, and other stats[]

Five of your six attributes (Strength, Dexterity, Constitution, Intelligence, and Charisma) 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 black dragon, your strength will be 18/**. If you eat a killer bee corpse, your strength may be reduced to 18/97, but after returning to an old form, your strength will again be 16. Wisdom is the only attribute which persists between forms.

If polymorphed to a strong monster (i. e. a dragon), your strength becomes 18/** until you return to an old form.

Things are different with intrinsics. As a monster, you will enjoy all intrinsics which you had before you polymorphed, all intrinsics of that monster, and all intrinsics 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 polymorphed to a dragon before you got poison resistance, it is a good idea to eat killer bees: the poison resistance which you acquire will stay with you, while the decline in your strength will not.

Hunger is not affected by polymorph or returning back. Even if you polymorph to a non-eating creature when fainting, you will continue to faint without a way to satiate your hunger.

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.

Polymorphing from human to human etc.[]

Polymorphing to your own race is a special case. Instead of being temporarily polymorphed to a monster, you see the message "You feel like a new (man, woman, elf, etc.)" and your parameters are randomly changed:

  • It adjusts your experience level by -2 to 2 levels.[4]
    • 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 amulet of life saving, you restore your old experience level, and no further changes applied.
    • If the new level is lower than the old one, it cannot be cured by blessed potion of full healing.
    • Your innate properties, resistances, and #enhance weapon slots are adjusted to match your new level.
  • It grows or shrinks your maximal hp (over the first 10 points) and energy, in proportion to your level change, then applies a further adjustment of -9 to 9 points.[5]
    • If your new maximal energy is negative, it becomes 0.
    • Your current hp and energy are adjusted proportionally to the change of maximal hp and energy.
  • You have a 10% chance to change sex.
  • Your strength, dexterity, constitution, and charisma change by -2 to 2 points (attrib.c).
  • It sets your hunger to a random value from 500 to 999.[6]
  • It cures both sickness and food poisoning (by calling potion.c with SICK_ALL).
  • It cures stoning, if you had been stiffening.
  • It would cure sliming, but slime remains on your body, thus the sliming process restarts and you have 10 turns to live.[7] (The DevTeam Thinks Of Everything.)
  • If your new current or maximal hp is 0 or negative, but you have polymorph control, they become 1 instead.
  • If your new current or maximal hp is 0 or negative, and no polymorph control, you die but can be saved by amulet of live saving.

There is nothing in this part of the source code to cure blindness (is this correct?) or to remove intrinsics that you gained from outside (for example by eating the corpse of a floating eye).

This process has curing effects, but for healthy adventurers, the DevTeam seems to have intentionally designed this function such 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, the luck integer has no effect here. You also cannot use a unicorn horn or other such cure to regain any lost levels or attributes. The comment at line 144[8] 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 (or new gnome) many times is no way to raise your experience level or your attributes.

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 man" like in a previous section.

Polymorphing to a monster while being another or the same monster is equivalent to returning to your human form and immediately polymorphing to the target monster. If you polymorph to a monster while being the same monster, you see the message "you feel like a new (monster)".


A ring of polymorph and a ring of polymorph control allows a low level character to become more powerful. Good options for polymorphing include:[9]

Hit dice Armor class
  • greater than 14 = Excellent
  • 12 to 14 = Very good
  • 9 to 11 = Good
  • 7 to 8 = Mediocre
  • 5 to 6 = Poor
  • 1 to 4 = Very poor
  • less than -3 = Excellent
  • -3 to -2 Very good
  • -1 to 0 Good
  • 1 to 3 Mediocre
  • 4 to 6 Poor
  • 7 to 10 Very poor
Creature Pros and cons
gargoyle If you are turning into stone, polymorphing into a gargoyle will stop the stiffening process. Also useful for safely killing cockatrices.
  • + Good attacks (2d6+2d6+2d4).
  • + Excellent armor class (-4).
  • + Strength 18/**.
  • + Can wear all armor.
  • + Stone resistant, doesn't breathe, doesn't eat.
  • - Poor hit dice (6).
  • - Slower than normal speed (10).
winged gargoyle If you are turning into stone, polymorphing into a winged gargoyle will stop the stiffening process. Also useful for safely killing cockatrices.
  • + Very good attacks (3d6+3d6+3d4).
  • + Good hit dice (9).
  • + Very Good armor class (-2).
  • + Fast, strength 18/**.
  • + Can wear helm and boots.
  • + Stone resistant, doesn't breathe, doesn't eat.
  • + Winged gargoyle can fly and lay eggs (although these mostly turn into regular gargoyles).
  • - You will break your shirt, body armor, and cloak.
Adult Dragons (various) Silver dragon is arguably the most powerful fighting form of dragon due to its intrinsic reflection. Gray dragons have magic resistance, but the benefits are lessened since polymorph traps are no longer a dangerous threat (due to you having polymorph control). It is possible, albeit difficult, to create silver or gray dragon scale mail by polymorphing into one of these forms. Unless you are a female character initially, you'll have to polymorph repeatedly until you turn into a female form of the dragon, and then #sit to produce eggs. Raise the pet baby dragons until they turn into adults, and then have them killed. They might leave dragon scales, which can be turned into dragon scale mail using a scroll of enchant armor.

If you lack poison resistance, you can easily gain it by polymorphing into a green dragon and eating poisonous corpses. Although the green dragon is poison resistant, you can still permanently gain the intrisic by eating poisonous corpses ("You feel especially healthy.").

  • + If already wearing dragon scales or mail, you become that dragon.
  • + Good attacks (B+3d8+1d4+1d4).
  • + Excellent hit dice (15).
  • + Good armor class (-1).
  • + You will have an intrinsic depending on your color.
  • + You can fly and have strength 18/**.
  • + You can lay eggs to produce good pets.
  • + You have a breath weapon (although it has limits).
  • - Cannot wear any armor nor wield any weapon. (Dragons can, however, wear rings on the foreclaws and an amulet)
  • - You will break your shirt, body armor (except dragon scale mail), and cloak.
  • - Don't attack cockatrices (except as a yellow dragon; yellow dragons are resistant to stoning).
  • + Good attacks (W2d8+M0d0)
  • + Very fast.
  • + Excellent hit dice (16).
  • + Very good armor class (-3).
  • + Strength 18/**.
  • - You will break your shirt, body armor, and cloak.
  • + Excellent attacks (2d10+2d10+2d10+2d10).
  • + Fast.
  • + Excellent hit dice (15).
  • + Very good armor class (-2).
  • + You can fly and have strength 18/**.
  • + You can wear boots, shield, helm
  • - You will break your shirt, body armor, and cloak.
  • - Don't attack cockatrices.
  • + Excellent attacks with weapons (W2d4+W2d4) plus claws (2d4+2d4+2d4+2d4).
  • + Excellent armor class (-6).
  • + Low base level (7) allows low level characters to stay polymorphed for the normal duration
  • + Fire and poison resistant, see invisible.
  • +/- mediocre hit dice (7)
  • - You will break your shirt, body armor, and cloak.
  • - Cannot wear boots.
master mind flayer
  • + Brain sucking does excellent (5d10) damage against monsters with brains. Beware of monsters with helmets!
  • + You gain nutrition without risk of choking when sucking brains
  • + Good hit dice (9).
  • + Good armor class (0).
  • + You can fly.
  • + Can wear all armor.
  • - Overeating from brain sucking abuses dexterity, increases risk of instadeath choking from eating.
  • - Comparatively weak attack against non-brained monsters (1d8), although you can wield a weapon.
  • - Don't attack cockatrices.
  • - Often an early genocide choice.
lich, demilich, master lich
  • + Good attacks (1d10C+M0d0m, 3d4C+M0d0m, 3d6C+M0d0m).
  • + Good, very good, and excellent hit dice (11, 14, 17).
  • + Good, very good, and excellent armor class (0, -2, -4).
  • + Can wear all armor.
  • + Can summon other liches.
  • + Cold, sleep, poison resistant; master lich is fire resistant.
  • + Doesn't breathe, doesn't eat, undead, regenerates.
  • - Often an early genocide choice.
vampire, vampire lord
  • + Will drain levels from most other monsters.
  • + Good and very good hit dice (10, 12).
  • + Mediocre and good armor class (1, 0).
  • + Can wear all armor.
  • + Sleep and poison resistant.
  • + Fast, strength 18/**.
  • + Doesn't breathe, doesn't eat, undead, regenerates.
  • + You can fly.
  • - Don't attack cockatrices.
  • - Vulnerable to silver.
Creatures with unusual attacks
  • + You can lay eggs to produce good pets.
  • + You can stone most other monsters.
  • + Poison and stone resistant.
  • - Poor hit dice (5) and poor armor class(6).
  • - You will drop your weapon and all armor.
wood nymph, water nymph, mountain nymph
  • + You can steal objects from other monsters.
  • + You can remove an iron ball and chain.
  • + You can teleport.
  • + Doesn't eat, can wear all armor.
  • + Water nymph can swim.
  • - Very poor hit dice (3) and armor class (9).
purple worm
  • + You can engulf and digest most other monsters.
  • + You can lay eggs to produce good pets.
  • + Excellent hit dice (15).
  • - Poor armor class (6).
  • - You will break your shirt, body armor, and cloak.
  • - You will drop your weapon, gloves, shield, helmet, and boots.
  • - You can be stoned by engulfing cockatrices or Medusa.
  • - Not good for attacking groups of monsters.
succubus, incubus
  • + You can steal objects from other monsters.
  • + Good armor class (0).
  • + Doesn't eat, can fly, can wear all armor.
  • + Fire and poison resistant.
  • - Poor hit dice (6).
Creatures with useful functions
gelatinous cube
  • + You can eat organic rings.
  • + You can paralyze most other monsters.
  • + Fire, cold, shock, sleep, poison, acid, and stone resistant.
  • - Poor hit dice (6) and very poor armor class (8).
  • - You will drop your weapon and all armor.
rock mole
  • + You can eat metallic rings and amulets.
  • + You can dig through walls.
  • - Very Poor hit dice (3).
  • - You will drop your weapon and all armor.
umber hulk
  • + Can dig through walls.
  • + Can confuse most other monsters.
  • - You will break your shirt, body armor, and cloak.
  • - Don't attack cockatrices.
  • + You can eat metallic rings and amulets.
  • + You can phase through most terrain.
  • + Good attacks (1d3+1d3+1d3+4d6).
  • + Very good armor class (-2).
  • + Strength 18/**.
  • + Fire, cold, and stone resistant; doesn't breathe.
  • - You will break your shirt, body armor, and cloak.

Monster versus adventurer polymorphs[]

NetHack treats the situation differently depending on whether you (as the adventurer) or a monster polymorphs.

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

An interesting case of this is lycanthropy. If you have this condition, you will sometimes polymorph into a canine (a jackal, for example). There is also a monster in the game called a werejackal, which in its human form will also sometimes become a jackal. As the jackal, either you or the monster can summon allied jackals as help. (If you summon them, then you keep the jackals as pets.) The similarity ends when as the jackal, you or the monster lose all of your health. You will become your normal race again, while the monster will die without transforming back into a human.

SLASH'EM changes the behavior from vanilla NetHack. In SLASH'EM, monster polymorphs behave more like player polymorphs in that monsters who are killed while polymorphed will revert to their original form. Polymorphed items will also return to their original forms after a certain amount of time.

Restrictions on polymorphing[]

Certain monsters are off-limits to polymorph,[10] either by you or a monster; these include:


Polymorph in SLASH'EM functions in a considerably different way than in vanilla Nethack. In SLASH'EM, all polymorph operations are temporary; this includes the polymorphing of monsters into other monsters and the polymorphing of objects.

When a monster that has been polymorphed into another monster (by wand, spell, trap, etc.) is destroyed, it reverts to its original form with reduced HP. Thus, it is no longer possible to slay dangerous enemies such as shopkeepers with polymorph (though you may be able to disable, immobilize, or slow them enough to rob them without killing them). Note that monsters such as chameleons and lycanthropes are much harder to kill under this system because they have the option of reverting to a different form during combat. Furthermore, you will not be able to permanently upgrade your pet with polymorph.

If you polymorph into an intelligent monster with an attack that requires direct contact (biting, tentacles, etc), you will not use this attack against petrifying monsters, as opposed to being instantly stoned. Attacking bare-handed will still stone you, however.

Polymorphed objects in SLASH'EM will also, eventually, revert, making polypiling of rings, wands, and equipment much less effective (and potentially dangerous—if, for example, you start wearing an amulet of life saving that used to be an amulet of strangulation). However, a polymorphed object in SLASH'EM can be fixed to its new form by being dipped in a potion of restore ability. Objects that vanish after a single use, such as potions and scrolls, will operate normally, and the fact that they would have reverted does not change the effect they do have.

SLASH'EM features a new monster, the genetic engineer, whose attack polymorphs you.

When a player polymorphs into a xorn in SLASH'EM, then returns to his or her original form, the player will be stuck in a pit that disappears after scrambling out. Presumably, this is to simulate the xorn's partial immersion in the surrounding earth.

Source code references[]