Monsters can only cast spells if they are not cancelled and at least level one, and can only cast once every (10 − (monster's level)) turns to a minimum of two turns; they will attempt to cast spells if these conditions are not met, producing a "curse" message. Even with these conditions satisfied, there is a 2 in (monster's level) chance of the spell failing (with five times that chance if the monster is confused).
Monsters that are scared (e.g., by Elbereth) or are not adjacent to you will not use directed spells. If a monster uses a directed spell at you, but you are on a different square than the monster expected, the spell will fail and produce a "curse" message.
|Foo points at you, then curses.||The monster attempted to cast a spell before they were able to do so.|
|Foo points all around, then curses.|
|Foo points and curses in your general direction.||As above, but the monster cannot see you.|
|Foo points and curses at your displaced image.||As above, but you are displaced.|
|You hear a mumbled curse.||As above, but you cannot see the monster.|
|The air crackles around foo.||The monster cast a spell when able to do so, but the spell failed.|
|Foo casts a spell!||The monster successfully cast a spell.|
|Foo casts a spell at you!|
|Foo casts a spell at a spot near you!||As above, but the monster cannot see you.|
|Foo casts a spell at your displaced image!||As above, but you are displaced.|
There are three categories of spells that monsters can cast: ray-type spells, mage spells, and clerical spells. In vanilla, no creature casts spells in more than one category. In the tables below, Min. level refers to the minimum level required for the monster to be able to cast that spell. The monsters that use the type of spells in each table are listed in the two Monsters column. In the Monsters (at lowest level) column, we assume that the monster is generated at its base level minus one, which is the lowest possible level at which a monster will be randomly generated. In the Monsters (at highest level) column, we assume that the monster is generated at its base level times 3/2, which is the highest possible level at which a monster will be randomly generated. In both cases, each monster can cast the spell on the line it appears, as well as every spell above it. It is still theoretically possible for monsters to cast spells that appear below their names in the table, if they drink enough potions of gain level. The spell Double Trouble can only be used by the Wizard of Yendor. As an example, a golden naga is guaranteed to be able to cast Psi bolt, Cure self, Haste self, Stun, Disappear, Drain strength and Destroy armor. It may be able to cast Curse items and Aggravate, if it is generated at a high enough level.
Monster spellcasting abilities are dependent on their current level, not their original level, so draining a monster will remove its ability to cast higher-level spells. However, most important spellcasters are immune to life drainage, and those that aren't generally have very high MR, making the spell nearly useless. Stormbringer and the Staff of Aesculapius bypass monster MR, though both will kill most non-resistant monsters quickly enough that the effect on their spellcasting is not generally that noticeable.
|Spell||Min. level||Directed||Monsters (at lowest level)||Monsters (at highest level)|
|Psi bolt||1||Y||kobold shaman|
|Cure self||2||barrow wight, orc shaman, gnomish wizard|
|Haste self||3||kobold shaman|
|Stun||4||Y||guide, apprentice||barrow wight, orc shaman, gnomish wizard|
|Drain strength||7||Y||guide, apprentice|
|Destroy armor||9||Y||golden naga, lich, nalfeshnee|
|Aggravate||14||ki-rin, titan, Ixoth, Dark One, Minion of Huhetotl, Thoth Amon, Chromatic Dragon, Nalzok||golden naga|
|Summon nasties||16||master lich, Archon, Neferet the Green||lich, nalfeshnee|
|Touch of death||21||Y||arch-lich, Orcus, Dispater, Demogorgon||demilich, master lich, arch-lich, ki-rin, titan, Archon, Ixoth, Dark One, Minion of Huhetotl, Thoth Amon, Chromatic Dragon, Nalzok, Neferet the Green, Orcus, Dispater, Demogorgon|
|Double Trouble||19/unique||Wizard of Yendor||Wizard of Yendor|
|Spell||Min. level||Directed||Monsters (at lowest level)||Monsters (at highest level)|
|Curse items||10||Y||aligned priest|
|Geyser||14||Y||high priest, Grand Master, Master Kaen, Arch Priest||aligned priest, high priest, Grand Master, Master Kaen, Arch Priest|
Ray-type spells come in three varieties (though only two are in use). They can be cast from afar, and when used this way, act the same as wands or breath weapons. When cast from an adjoining square, they act as melee attacks and cannot be reflected, but the appropriate resistance will still nullify them.
- Three creatures use magic missile: Angels, Yeenoghu and the Oracle (the Oracle's version is passive and will only occur in response to a melee attack). Magic resistance is proof against this attack. The message is, "You are hit by a shower of missiles!" "The missiles bounce off!" if you have magic resistance.
- Asmodeus, and no one else, has a cold attack. "You are covered in frost" when hit by this attack. Cold resistance nullifies it.
- The source code also supports a fire attack. "You are enveloped in flames" when hit by this attack, and fire resistance nullifies it. No monster in vanilla has this attack, but in SLASH'EM it is used by fire vampires.
SLASH'EM has many new spellcasting monsters. It also introduces two new mage spells:
- Call undead, which can be used by all liches (and no other monsters);
- Create pool, which can be used by monsters of level 13 or higher.
Slash'EM Extended reduces the chances of spellcasting monsters to actually cast spells, especially if the spell summons hostile monsters. However, it also introduces an array of new clerical spells. All of these can be used by monsters of level 9 or higher unless otherwise noted.
- Antimatter storm (monster needs to be level 14 or higher), doing erosion damage to the player's entire inventory, including unerodable items like black dragon scale mail and rustproof splint mail;
- Petrify (monster needs to be level 14 or higher), causing the player character to start turning to stone (7 turns to live);
- Sliming (monster needs to be level 14 or higher), generating the "You don't feel very well" message; the player starts turning to slime (100 turns to live);
- Summon Elm (monster needs to be level 14 or higher), creating a hostile minion of a random god that will start attacking the player;
- Intrinsic loss, which can remove a random intrinsic (similar to being hit by a gremlin);
- Aggravate monster (copy of the arcane spell);
- Dark aura, causing the area around the player to become unlit;
- Acid trip, making the player hallucinate for some (more) turns;
- Create traps, creating random traps around the player's location;
- Relocation, teleporting the player to a random empty location on the level, bypassing teleport control and no-teleport restrictions;
- Mana drain, reducing the player's current Pw and sometimes maximum Pw as well;
- Disengrave, removing an active Elbereth engraving underneath the player;
- Disarm, removing the player's weapon from their hands;
- Slow, removing speed intrinsic and non-permanent extrinsics;
- Dementor force, lowering the player's luck and alignment record;
- Punishment, chaining the player to a heavy iron ball (if one already exists, it is made heavier instead);
- Garbage spam, surrounding the player with items, doors and staircases that are actually mimics;
- Charming seduction, summoning nymphs around the player which may immediately begin stealing items;
- Piercing ceiling, summoning piercers around the player;
- Rat swarm, summoning a bunch of rodents;
- Demonic spiders, summoning a bunch of spiders (which often start out concealed under an item);
- Can of worms, summoning a bunch of worms (may also start out concealed);
- Flapping bats, summoning a bunch of bats;
- Hulking brutes, summoning umber hulks and shambling horrors (very dangerous due to their randomized attacks);
- Court summoning, summoning human enemies (ones represented by @), including werecreatures and player-character monsters;
- Golem mastery, surrounding the player with random golems;
- Deep sea trouble, creating eels (very dangerous if there is water on the level);
- Mystic nature, creating arctic fern spores, killer tomatoes and other monsters represented by the % character.
Also, the Geyser spell will cause the player's inventory to become wet, and on a lethe level possibly disenchant items or transform them into potions/scrolls of amnesia. There are also the following new arcane spells, which can be cast by monsters of level 9 or higher unless otherwise noted:
- Damage armor, which works like destroy armor but only damages a worn armor item by one stage (can destroy the item if it was thoroughly eroded already), and fooproof armor items resist;
- Wither, which works like damage armor but also damages and eventually destroys fooproof items as well as those outright immune to damage (dragon scale mail for example);
- Megaload, requires the monster to be at least level 13; this spell adds a cursed loadstone to the player's inventory;
- Levitate, requires the monster to be at least level 13; this spell causes the player to float in the air for a period of time, preventing them from picking up items;
- Summon Ghost, requires the monster to be at least level 19; the player is surrounded by stronger versions of regular player monsters. If there are entries in the high-score file, the names and classes of these monsters are directly taken from there; the first 1000 entries in the list are eligible for selection. If no entries exist, random player monsters with random names (taken from a preset list) are created instead.
- Enrage, requires the monster to be at least level 22; this spell heals all hostile monsters in a certain radius around the player, causes peaceful monsters to become hostile, and has a chance of making tame monsters hostile as well. The chance of the latter happening is much higher if a tame monster has been abused or its tameness is low;
- Divine wrath, requires the monster to be at least level 23; the player's god becomes angry (randomly increases anger by 1-3 points) and smites the character.
The Call Undead arcane monster spell isn't restricted to liches in Slash'EM Extended. Instead, all arcane spellcasters that are at least level 10 can cast it. Also, the Wizard of Yendor has a small chance of casting Triple Trouble if there are two active wizards in the game.
- mcastu.c in NetHack 3.4.3, line 214
- mcastu.c in NetHack 3.4.3, line 208
- mcastu.c in NetHack 3.4.3, line 232
- src/mhitu.c in NetHack 3.6.1, line 772: if monster is at range, buzzmu() is chosen which only handles ray-type spells
- src/monmove.c in NetHack 3.6.1, line 570
- mcastu.c in NetHack 3.4.3, line 270