When cast, a number of hostile nasties will be generated around the target; this can be affected by displacement or invisibility, depending on the caster. Monsters are created until either d(XLvl) nasties which are neutral or co-aligned with the summoner have been created, or the maximum of 10 nasties have been created. Because of this, monsters of alignments with fewer co-aligned nasties will summon more nasties on average. Summoned monsters will be unable to use special attacks such as breath weapons for d4 turns.
If this spell is cast in Gehennom, it is treated as if the Wizard of Yendor were summoning regardless of the caster, and there is a 1⁄10 chance that a demon is summoned - thus, anyone capable of casting the spell encountered in Gehennom can summon a demon lord or prince this way. Both this and remote summoning by the Wizard of Yendor are considered neutral for this purpose.
Summoned spellcasters will have a lower difficulty than the caster. & will not summon A, and vice versa. On the Rogue level, nasties not represented by an uppercase letter are less likely to be summoned.
Monsters summoned in this fashion respect genocide, but not extinction: If a genocided monster would be summoned, it is replaced by an ordinary random monster (which is not guaranteed to be hostile). Spellcasting monsters generated this way need not be lower in difficulty than the caster.
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.
Spellcasters casting summon nasties can no longer summon monsters of equal or higher difficulty than themselves. Thus, Archons cannot summon more Archons, arch-liches cannot summon more arch-liches, and so on.
If a genocided monster with a pre-grown form (that is not explicitly a baby form) is chosen, and this form is not also genocided, it will appear in place of the genocided monster. For example, mind flayers can appear in place of genocided master mind flayers. This also happens if the chosen nasty is inappropriate for the location, such as an arch-lich outside Gehennom.Also, when the difficulty is high enough to summon arch-liches or Archons (e.g., the Wizard casting it or via random harassment), at most one arch-lich OR one Archon will be created by a single summon nasties. See commit 3eed500 for more details.
Dealing with this spell can require action both before and after it is cast:
One option is to genocide the worst nasties: arch-liches and master mind flayers are good candidates for this. However, if the spell attempts to generate a genocided monster, it will instead generate a random one. Once the player has the Amulet of Yendor and is out of Gehennom, Archons and ki-rin are not unlikely random monster choices and may be summoned in place of genocided monsters.
One good option for a player with a scroll of genocide would be to blessed-genocide L. Liches are by far the most frequently encountered casters of summon nasties, and also the only ones that can be genocided anyway. Doing so will genocide only one nasty, arch-liches, and so will not greatly increase the probability of worse nasties such as Archons being generated by the spell.
When meeting a summoner
The worst place to meet monsters with this spell is on large open levels, such as Juiblex's swamp. On such levels, a summoner will often sit outside of the ring of monsters it has created around you and continue summoning, even as you attempt to fight off its minions. In this situation, the covetous behavior can be helpful; an arch-lich that warps to the upstairs may no longer be in sight, whereas a fleeing demilich will remain in sight and continue to fill the level with nasties.
If you are unable to kill the caster and possess reflection and a permanent Elbereth, it is possible to wait on the Elbereth square for the caster to create a black dragon and wait for the disintegration breath to destroy the summoner, or possibly for a cockatrice to be generated and leave a corpse. This can be a life-saver if any of the demon princes appear as well.
Another way to counter the summon nasties spell is with a ring of conflict - the monsters will fight one another instead of focusing on you. A scroll of taming or spell of charm monster are also effective, although many nasties have a substantial chance of resisting either one.
- A monster appears from nowhere!
- One monster was summoned.
- Monsters appear from nowhere!
- Multiple monsters were summoned.
- <A monster appears/Monsters appear> around <a spot near you/your displaced image>!
- The summoner was fooled by your invisibility/displacement. The summoned monsters may still be able to find you.
- "Destroy the thief, my pet(s)!"
- The Wizard of Yendor cast the spell while alive. (The summon nasties effect that the Wizard uses to harass you in his absence displays no message.)
These monsters are "nasties" for the purposes of this spell:
Demons (in Gehennom only)
In versions prior to NetHack 3.6.1 and variants based on them, the monsters listed below qualified as nasties and were not restricted depending on alignment. Nasty selection on the Rogue level was not biased toward uppercase letters, and the number of nasties was simply d(XLvl).
- L arch-lich
- q baluchitherium
- D black dragon
- @ captain
- Y carnivorous ape
- c cockatrice
- A couatl
- R disenchanter
- @ elf-lord
- @ Elvenking
- H ettin
- E fire elemental
- H fire giant
- D green dragon
- P green slime
- g gremlin
- ' iron golem
- J jabberwock
- q leocrotta
- h master mind flayer
- H minotaur
- j ochre jelly
- O ogre king
- T Olog-hai
- Y owlbear
- w purple worm
- D red dragon
- T rock troll
- E stalker
- U umber hulk
- V vampire lord
- g winged gargoyle
- x xan
- X xorn
- D yellow dragon
- z zruty
In SLASH'EM, these monsters are also nasties in addition to those above:
The following monsters were removed from the list of nasties:
In FIQHack, monsters summoned via summon nasties exist for 20 turns before disappearing.
- wizard.c in NetHack 3.4.3, line 456
- src/wizard.c in NetHack 3.6.1, line 24
- src/wizard.c in NetHack 3.6.1, line 609
- src/wizard.c in NetHack 3.6.6, line 558
- wizard.c in NetHack 3.4.3, line 448
- src/wizard.c in NetHack 3.6.1, line 523
- src/wizard.c in NetHack 3.6.6, line 44
- wizard.c in SLASH'EM 0.0.7E7F2, line 26