# Xorn

X xorn 

Difficulty

11

Attacks

Claw 1d3, Claw 1d3, Claw 1d3, Bite 4d6

X xorn 

Difficulty

11

Attacks

Claw 1d3, Claw 1d3, Claw 1d3, Bite 4d6

Base level

8

Base experience

139

Speed

9

Base AC

−2

Base MR

20

Alignment

0 (neutral)

Frequency (by normal means)

1 (Very rare)

Genocidable

Yes

Weight

1200

Nutritional value

700

Size

Medium

Resistances

Fire, Cold, Stoning

Resistances conveyed

None

A xorn:

 can phase through walls.

 does not breathe.

 has a thick hide.

 can eat metal.

 is normally generated hostile.

 is strong.

Reference

monst.c#line2054

The xorn is a monster that appears in NetHack. It is the only member of the ​X xorn monster class. 
The xorn is notable for its ability to phase through walls and eat metal. Xorns are also unbreathing and resistant to fire, cold, and stoning.
Xorns are kebabable, granting a +2 to-hit bonus when using a weapon that uses the spear or javelin skills against them. They are also susceptible to digging attacks, granting a +2 to-hit bonus to when using pick-axes or dwarvish mattocks to attack them.

Contents

1 Generation
2 Strategy

2.1 Polyself

3 History
4 Origin
5 Variants

5.1 SLASH'EM
5.2 dNetHack
5.3 SlashTHEM

6 Encyclopedia entry

Generation
Xorns are rarely randomly generated and may not be encountered until much deeper within the dungeon or its branches; some xorns are likely to be generated in the throne room of the Castle at level creation. Xorns can also be generated on the Plane of Earth by digging with a pick-axe.
Xorns are the second quest monster for the Monk quest and Wizard quest; they also function as the Monk's second quest monster "class", and are thus slightly more common for them than Wizards.

Strategy
Xorns have a decent AC of −2 and four attacks including an extremely nasty bite, and their phasing can make them difficult to evade; players should not use non-disposable iron projectiles against xorns. However, they move at a slow 9 speed and respect Elbereth, so they can be dispatched with sufficient caution. Xorns can be lethal to players with low AC who try to out-melee them, particularly Monks embarking on their quest – their phasing can thwart boulder fort strategies employed against Master Kaen.
While xorns cannot cross moats and pools of water (such as the moat in the Castle), players polymorphed into xorns can – in the case of the Castle it is often enough to lure them across the drawbridge and raise it behind you if you are phasing or otherwise trying to avoid them. Xorns also cannot be destroyed by the drawbridge under normal circumstances due to their phasing; however, if there are two phasing monsters on both squares of the drawbridge (the portcullis and the moat in front), one of them will be killed if the drawbridge is raised.

Polyself
Due to their unusual abilities, xorns are one of the most useful monsters to polymorph into for various applications:

Eating jewelry for intrinsics
Phasing across difficult-to-navigate levels such as Asmodeus' Lair or the Stronghold of the Master Assassin - note that you cannot phase across the boundary between the two parts of Moloch's Sanctum, or anywhere on the Astral Plane
Heading directly to the wand of wishing in the Castle during a speedrun or with a weak character
Xorns can wear armor, but cannot wear body armor or cloaks; morphing into a xorn will destroy them if you are wearing any, so be sure to remove these items before making the transformation. Remember that you can cross water while polymorphed into a xorn, although other xorns cannot.
Additionally, be mindful of where you are when your polyself is potentially about to expire: If you return to normal form while phasing through a wall adjacent to open space, you will be able to move into it. However, if you return to normal form while phasing through the middle of solid stone with no adjacent space, you will be unable to move—if this happens you can teleport out, pray (since being stuck in a wall without having phasing is a major problem), or re-polymorph yourself into a xorn or earth elemental.

History
The xorn is introduced in Hack for PDP-11, a variant of Jay Fenlason's Hack.
In NetHack 3.4.3, xorns were subject to a few notable bugs:

Xorns could be created in inaccessible areas, such as outside the Sokoban walls. This was bug C343-151.
When a player polymorphed into a xorn returned to their normal form and was in open space, they would be stuck in a pit that doesn't exist; this was bug C343-17.
Origin

Wikipedia has an article about:
Xorn (Dungeons &amp; Dragons)

The xorn originates from Dungeons &amp; Dragons, where it debuts in the 1st Edition Monster Manual of Advanced Dungeons &amp; Dragons. Xorns come from the Elemental Plane of Earth and are depicted as odd and radially-symmetrical creatures: a large mouth sits at the top of their rocky body, surrounded by three long arms interspersed with their three eyes and three stumpy legs. All of their limbs are evenly spaced, and their arms end in sharp talons. 
Like many creatures from their Elemental Plane, xorns can travel through ground and stone as if it were water; xorns encountered outside their home plane are not especially peaceful, but typically only attack anything that attacks them first or else gets in the way of their scavenging for the usual xorn diet of stone and minerals (including some types of metals). This may explain the unused message present in the code of NetHack for eating flint stones.

Variants
SLASH'EM
In SLASH'EM, xorns hit as +2 weapons.

dNetHack
In dNetHack, the Elder Elemental Eye at any level of reinforcement can protect against xorns.

SlashTHEM
In SlashTHEM, on top of SLASH'EM changes xorns are additionally lithivorous and can eat stone in addition to metal.

Encyclopedia entry

A distant cousin of the earth elemental, the xorn has the
ability to shift the cells of its body around in such a way
that it becomes porous to inert material.  This gives it the
ability to pass through any obstacle that might be between it
and its next meal.

 