# Yellow light

y yellow light 

Difficulty

5

Attacks

Explode 10d20 blind

y yellow light 

Difficulty

5

Attacks

Explode 10d20 blind

Base level

3

Base experience

44

Speed

15

Base AC

0

Base MR

0

Alignment

0 (neutral)

Frequency (by normal means)

4 (Uncommon)

Genocidable

Yes

Weight

0

Nutritional value

0

Size

Small

Resistances

fire, cold, shock, disintegration, sleep, poison, acid, stoning

Resistances conveyed

None

A yellow light:

 can fly.

 can flow under doors.

 does not breathe.
 cannot pick up items.
 has no eyes.

 has no limbs.
 has no head.
 is mindless.

 does not have a solid form.

 does not eat. (*)
 is neither male nor female.
 is normally generated hostile.

 can be seen through infravision.

 never leaves a corpse.

 gives out light.

Reference

monst.c#line956

A yellow light, y, is a type of monster that appears in NetHack. It is the only other member of the light monster class along with the black light. A yellow light is amorphous, can fly and flow under doors, and possesses every resistance property minus magic resistance.
Yellow lights illuminate their surroundings in a 3x3 area centered on themselves. Their sole attack directs an explosion at the square of its target that destroys the yellow light - any target that is hit is blinded for 10d20 turns. The attack is much less effective on you if you cannot see the yellow light - if a yellow light is invisible and you cannot see invisible, there is an experience level-based chance that its explosion will not affect you.[1] A yellow light's explosion will wake nearby sleeping monsters.

Contents

1 Generation
2 Strategy
3 History
4 Messages
5 Variants

5.1 UnNetHack
5.2 xNetHack

6 Encyclopedia entry
7 References

Generation
Yellow lights are always generated hostile, and never leave a corpse upon death.
In addition to normal random generation, reading a non-cursed scroll of light while confused has a 1⁄5 chance of generating a black light unless they are genocided.
The second variant of Medusa's Island has a yellow light in the back room of the hall Medusa inhabits, and three yellow lights are generated on the Plane of Air.

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

Reading a non-cursed scroll of light while confused will instead summon multiple tame cancelled yellow lights if they are not genocided. An uncursed scroll will summon 3–4 yellow lights, while a blessed scroll will summon 5–6 yellow lights. This was adapted from UnNetHack.
Strategy
Blinding yourself, e.g. by wearing a blindfold or towel, will render the explosion harmless; various cures such as a unicorn horn or curative spell (e.g., extra healing and cure blindness) also make them trivial to deal with. Yellow lights also cannot see invisible - if you are invisible or have displacement, they may explode at an empty square with no effect.
While it is possible to kill yellow lights normally if you can deal with their 0 AC and fast, erratic movement, it is usually preferable to let them explode while already blinded as above in most scenarios. Be careful of dealing with yellow lights in or around rooms such as treasure zoos or throne rooms - a light that explodes close to the room will wake many (if not all) of the inhabitants.

History
Yellow lights have been present since Hack121, a variant of Jay Fenlason's Hack.

Messages
You get the impression it was not terribly bright.
An invisible yellow light exploded, and you were unaffected by it.
You have a melancholy feeling for a moment, then it passes.
A tame yellow light exploded.
Variants
UnNetHack
In UnNetHack, yellow lights are subject to special generation on the Oracle level, where only 93% of monsters are generated through normal means; of the remaining 7%, yellow lights have a 1⁄10 chance of being generated.
Reading a non-cursed scroll of light while confused will instead summon multiple tame cancelled yellow lights if they are not genocided. An uncursed scroll will summon 3–4 yellow lights, while a blessed scroll will summon 5–6 yellow lights.

xNetHack
In xNetHack, yellow lights emit a 2-square radius of light around themselves, and their explosion attack affects all monsters adjacent to it.

Encyclopedia entry

Strange creatures formed from energy rather than matter,
lights are given to self-destructive behavior when battling
foes.

 

References

↑ src/mhitu.c in NetHack 3.6.7, line 2100