A property is any of several on-or-off traits of the hero or a monster. Properties include the resistances, the effects of rings, the temporary effects of certain potions, negative effects (as confusion, stoning), and others. A property may be intrinsic or extrinsic.
A property is boolean; you either have it or you have it not. Thus numerical traits (as alignment record, dexterity, luck, prayer timeout, ...) are not properties in this sense. Enlightenment will reveal many properties of the hero, along with some other traits.
Intrinsic versus extrinsic
You gain an extrinsic when you wield, wear or put on an item that provides it. The item is typically a ring, amulet, armor or artifact. For example, either the amulet of ESP or the helm of telepathy grants extrinsic telepathy. The extrinsic goes away when you take off the item. Some nice quest artifacts provide an extrinsic when carried; in that case, the extrinsic goes away when you drop or lose the artifact or place it in a container.
There are more ways to gain an intrinsic.
- You might gain it as an innate property of your role or race. For some innate properties, you need to first reach a certain experience level. For example, a Barbarian starts with poison resistance and gains intrinsic speed at level 7.
- You might gain it "from outside". The principal ways to do this are crowning, eating certain corpses, eating jewelry or sitting on thrones.
The gremlin has an attack that steals a random intrinsic. Also, you can lose an innate property if something drains you below the required level.
List of properties
The following tables provide a brief description of each property that the hero might have, and some notable sources of that property. (The property may have other sources.) The individual articles for each property might provide more details.
The left column also gives the associated constant from prop.h, if any. The right column may refer to a monster flag (like M1_FLY); then you may search monst.c to find a monster with that flag for polymorph.
It is possible to receive any of these properties as intrinsics that never time out. Some are also available as extrinsics, or as temporary intrinsics. This list includes each property that may be intrinsic, even if the only way is to eat the correct ring. (Eating a ring has a chance of failing to convey the property!)
|Prevents fire damage, but does not fireproof your inventory.|
|Prevents cold damage, but does not protect your potions.|
|Prevents sleep. Alternatively, free action works for potions only.|
|Prevents instadeath from black dragon breath (or use reflection to block the breath); also the only way to prevent instadeath from wide-angle disintegration beams.
|Prevents damage from electric attacks, but does not defend rings or wands.|
|Prevents poisoning, also prevents the instadeath from poison.|
|Increases the rate of recovery of your hit points, so that they sooner return to maximum.|
|Automatically search squares around you, increasing the chance that you notice hidden doors or traps.|
|Allows you to see invisible monsters (and in SLASH'EM, invisible objects).|
|Makes you invisible. Monsters may struggle to find you and miss with their attacks.|
|Every few turns, randomly teleports you around the dungeon level.|
|When you teleport, allows you to choose your destination tile.|
|Every few turns, randomly polymorphs you into another monster type.
|When you polymorph, allows you to choose the type of monster to become.|
|You float in the air, and cannot reach the floor! However, you can pass over moats, trap doors and pits (except the pits in Sokoban with air currents).|
|Allows you to move around quietly, so that your steps do not wake sleeping monsters.|
|Increases probability that nearby sleeping monsters notice you and wake.|
|Monsters will attack other nearby monsters (including you), disregarding their tame/peaceful/hostile status.|
|Indicates that you either have intrinsic divine protection, or wear an item of protection, for the purpose of the enlightenment message.|
|protection from shape changers
|Forces shapeshifters and chameleons to stay in normal form.
|Labels unseen, undetected nearby monsters with a danger indicator from 1 to 5.|
|Increases the rate that you lose nutrition. This is bad, unless you are trying to make room for your next meal.
|Intrinsic telepathy allows you to sense most monsters (except mindless monsters), but only when you are blind.
Extrinsic telepathy also functions in a limited radius when you are not blind.
|Intrinsic speed makes you fast, allowing four moves for every three turns.
Extrinsic speed, and temporary intrinsic speed, make you very fast, allowing five moves every three turns.
|food appraisal||Before eating something, warns you of any bad effects that might result, and allows you to abort. Lost after activating once.|
|Allows you to survive without breathing. You can go underwater. You will not choke on your food.
|amphibiousness||Allows you to breathe both in the air and underwater. You can go underwater.|
|Allows you to land on another tile in one move.|
|Your eyes sense the heat from warm monsters, making them visible to you, even in dark places.|
There are no sources that provide any of these properties as an intrinsic (without polymorphing), but there exist extrinsic sources, or you may polymorph into a certain monster to gain the property.
| Common name
| acid resistance
|Prevents acid damage (from yellow dragon breath, or from eating acidic corpses), but does not rustproof your armor.|
| stoning resistance
|Prevents the stoning process. This is one way to fight cockatrices and chickatrices.|
|sliming resistance||Provides immunity to the sliming process; this protects against the slime attack of the green slime.|
| drain resistance
|Protects against loss of experience levels, for example from the drain life attack of monsters. Prevents instadeath from drain below level 1.|
|Indicates that you wear a ring of adornment (of any enchantment). This intrinsic allows an enlightenment message to be displayed.|
|Bounces gaze and ray attacks away from you, so that they do not affect you.|
| life saving
| When you die, the worn amulet of life saving will resurrect you.
| magic resistance
|Prevents damage from certain traps, from magic missile and certain other magic attacks, and rays/fingers of death, among other useful benefits.|
|You can walk through walls. This is useful for taking shortcuts without digging them, and fleeing from certain places. However, this property has no effect in Sokoban.|
| hallucination resistance
| Prevents the effects of hallucination.
| Causes you to sometimes trip while walking, accidentally drop items, fall down stairs, and have other such problems.
| water walking
| You can cross water by walking on its surface (as an alternative to using levitation, magical breathing or swimming). If the boots are fireproof, they may also be used to cross lava.
| Produces a displaced image of you on a nearby square, such that monsters sometimes attack the image and miss you.
| Every few turns, the map of the area around you appears in your mind. This helps explore new areas and discover hidden paths.
| energy regeneration
|Your power increases toward maximum at a much faster rate, allowing you to frequently cast spells (if you have enough nutrition).|
| half spell damage
| half physical damage
| sickness resistance
|Provides complete immunity to sickness--both illness and food poisoning.|
| free action
| Prevents paralysis in most cases. Makes the potion of sleeping harmless, but does not prevent other forms of sleep. Reduces stunning from monster spells to one turn.
|Enables you to swim across water. This differs from levitation (to float across water) and breathless (to go underwater).|
| sustain ability
| Prevents changes to your six attributes. Prevents the effects of exercise and abuse.
|Enables you to fly above the ground. Flight is better than levitation, because you may reach the ground and fly down stairs.|
| Holds you to your current form. Use this to prevent unwanted polymorph, or to remain forever in your polymorphed form.
| slow digestion
| Decreases the rate that you lose nutrition, allowing you to survive longer before starvation. Also prevents purple worms from digesting you.
| warned of monster type
| Detects all monsters on the dungeon level that match certain monster types.
Intrinsics that always time out
You may receive any of these properties in this table as a temporary intrinsic, but not as a permanent intrinsic. After a specific number of turns, you lose the temporary intrinsic. That may be well, because most of these properties have bad effects; you would want them to wear off over time.
| Common name
|Movement commands may cause you to step in a random direction, and you may hit pets by mistake. Direction of Zapping, spellcasting and firing also has a high chance of being randomized. Prevents teleport control.|
|Among other effects, you will mispronounce any scroll that you read (causing the scroll to have an alternate effect), and you will have trouble with spells and spellbooks.|
|Disables your eyes, blocking your sight (unless you wear the Eyes of the Overworld). Intrinsic blindness will heal eventually, or you may use a cure such as a carrot.|
| restful sleep
| You keep falling asleep.
|paralysis|| You become immobile and miss a number of turns.
| wounded legs
|Gives a random appearance to any monster or object on the map, so that you do not know who or what you see. In SLASH'EM, hallucination also distorts the view of objects on the same square as you, including your inventory.|
| slippery fingers
|Causes wielded objects to drop from your grasp.|
|Blocks all damage and prevents most causes of death.|
| monster detection
|Detect all monsters on the dungeon level. This property is only available as a temporary intrinsic.|
Intrisics that time out, then cause harm
These temporary intrinsics do not only time out and go away, they also cause do something (typically to cause instadeath) when they time out. When you have one of these properties, you only have some number of turns to remove the property and avoid its time-out effect.
| Common name
|A fatal illness; you must cure this or it becomes an instadeath.|
| Gradual stiffening will turn you into a statue (causing instadeath).
|Can cause stun and confusion; when nausea times out, you spew part of your food and lose some nutrition.|
| Your amulet will strangle you to instadeath in five turns, unless you can somehow remove it before then.
|Green slime will overtake your body and kill you, unless you can somehow remove the slime or gain sliming resistance before that happens.|
The adjective intrinsic refers to something that is internal, inherit, within the body. We also use the term as a noun. The antonym of intrinsic is extrinsic.
Oddly, sometimes we also use the term "intrinsic" to refer to any property, whether that property is intrinsic or extrinsic. For example, we might refer to an "intrinsic" from a ring, though the ring is external to the character. This leads to oxymoronic phrases such as "extrinsic intrinsic".
The usage of "intrinsic" to mean "extrinsic" occurs in other pages on this wiki, and even within the source code of NetHack. For example, the comment at the top of wield.c refers to wielded weapons conveying intrinsics, though they would actually convey extrinsics. The set_artifact_intrinsic function in artifact.c is another example of this usage. The mintrinsics field of struct monst stores information about both intrinsic and extrinsic resistances of the monsters.
One can justify the use of "intrinsic" to mean "extrinsic". For example, an amulet versus poison may be extrinsic to your body, but when you wear it, the effect spreads inside your body and becomes intrinsic. When you eat that kobold shaman corpse, or land on poison in a spiked pit, then the poison enters your body but has no effect. There must be some intrinsic defense in your body that stops the poison, though the ring remains outside on your finger. This explanation would not work so well for an amulet of reflection.
If you quaff a potion that provides a property, it is an intrinsic or extrinsic property? One argument states that the contents of the potion enters your body, so the property must be intrinsic. (A look at struct prop supports that argument.) The other argument states any property from an item, including a potion, is an extrinsic. The potion of blindness seems to grant intrinsic blindness (not extrinsic blindness, which you could #wipe away), but the potion of speed seems to grant extrinsic speed, equivalent with speed boots.
If you acquire a property through polymorph, it is an intrinsic or extrinsic property? One argument notes that the property is intrinsic to your current form; the other argument provides that your current form is extrinsic to your true form.
For details, see prop.h
The source code defines most of the properties at prop.h, line 8. Each property has a representative integer constant. Particularly in objects.c and artilist.h, the integer constants assign the properties granted by using certain items. The integer constants also serve as array indexes into the u.uprops, an array of struct prop that records the source of each of the hero's intrinsics and extrinsics.
- mhitu.c, line 1524, mondata.h, line 51
- mondata.c in NetHack 3.4.3, line 73
- timeout.c in NetHack 3.4.3, line 51
- monst.h, line 63, mondata.h, line 14, mondata.c, line 23, worn.c, line 260
- NetHack 3.2.0/you.h, line 108, NetHack 3.3.0/prop.h, line 78