A gas spore will not attack on its own and is rather slow, but acts as a "living mine" that dies in an explosion when its HP is depleted and hits all squares adjacent to it. Being caught in the explosion of a gas spore deals 4-24 damage and abuses your strength; killing the gas spore yourself will also credit you for any monsters hit or killed by the explosion, as well as penalizing you for angering or killing peaceful monsters. Instadeath that ignores HP, such as from deadly poison or a wand of death, does not cause the gas spore to explode.
It is perfectly fine to simply avoid attacking gas spores altogether, as they are incapable of attacking you. However, other monsters may accidentally cause a gas spore explosion with ranged attacks or an attack prompted by conflict; pets in particular will begin attacking gas spores once they are high enough level, which may endanger you if you are not similarly high-level.
The best strategy when faced with a gas spore that you can reasonably fight (or else cannot avoid) is to step back and use whatever ranged attacks you have at your disposal - offensive spells, arrows, darts, or even throwing rocks and junk weapons. If you have no other options, no peaceful or tame monsters are nearby, and/or you have more than 24 HP along with good AC, you can take a chance and dispatch the spore with melee attacks.
Early-game Healers can use gas spores to train their weapon skills, such as the knife (via the starting scalpel) or the more common dagger, using a stethoscope to monitor the gas spore's HP and allow it to heal back up before attacking it again. While any role can do this, Healers are the only one guaranteed to start with the stethoscope.
As explained previously, the game considers you responsible for any damage done by a gas spore's explosion that you caused. This has a number of repercussions, depending on the monster that has been damaged:
- Pets killed by the gas spore explosion are treated as if you had killed them directly, i.e. -15 alignment and -1 luck.
- Peaceful monsters become angry, incurring a -1 penalty to alignment record, and you incur a -5 alignment penalty if the explosion kills a peaceful monster without angering it. On top of early alignment penalties hampering your odds of survival, shopkeepers, aligned priests and watchmen in particular will cause you plenty of grief if you anger them.
- However, other hostile monsters can be killed by the explosion - as you gain experience for each kill, this can possibly allow you to rise a quick level or two if the opportunity arises.
Gas spores are one of many threats to a protection racket that may warrant gaining a couple of levels prior to entering the Gnomish Mines, then level draining yourself once you successfully reach the Minetown temple.
The gas spore first appears in NetHack 3.3.0.
The gas spore originates from Dungeons & Dragons, where it is a type of spherical floating fungus with a central false "eye" and ten rhizome growths on its top, giving it a close resemblance to the beholder that causes it to be mistaken for the monster from a distance. The rhizome growths serve as feeding organs, and are used to extract lichen and mold from walls, leaves from trees and scum from the surface of ponds.
Gas spores were hollow, but their interiors contained a large number of spores kept under high pressure. A gas spore that was hit anywhere except the rhizome growths and damaged at all will explode, releasing poisonous gas and a large amount of spores within 20 feet - it can also spread its spores by making contact with the exposed flesh of any warm-blooded creature that is at least gnome-sized, dying immediately after. Victims that a gas spore infects die if they do not obtain a cure within 24 hours - the corpse of a being that succumbs to this infection then sprouts several tiny gas spores, which reached maturity within seven days.
Gas spores that grew upon the corpses of dead beholders were known to carry the memories of their host, which an infected humanoid could access. This may be a basis for in-universe beliefs that the spores first appeared as a result of parasitic fungi that fed off dead beholders and became infected with aberrant magic, adapting the ability quickly sprout from any infected corpse after a long period.
- You hear a blast.
- An gas spore exploded outside of your range of vision.
In SLASH'EM, 37 gas spores are generated within the Neutral Quest at level creation, and may be among the random e that can also be generated at level creation. They share the same exact glyph as the Beholder, e, which can prove deadly if you mistake it for one and fail to blind yourself against its gaze attacks.
One type of random vault that can be encountered is a "room with sessile growths", which may contain several gas spores.
In xNetHack, pets will not attack a gas spore if you are adjacent to it.
xNetHack also adds the "sessile growth" random vault as a themed room, and includes an additional themed room that is mostly or entirely filled with gas spores.
The attack by those who want to die
-- this is the attack against which you cannot prepare a perfect defense.