Spellbook of detect unseen
| spellbook of + detect unseen 
| |
|---|---|
| Appearance | random |
| Abundance | 2.0% |
| Base price | 300 zm |
| Weight | 50 |
| Turns to read | 10 |
| Ink to write | 15–29 |
| Spell type | divination |
| Level | 3 |
| Power cost | 15 Pw |
| Direction | non-directional |
| Equivalent | wand of secret door detection |
In NetHack, the spellbook of detect unseen can be read to learn the spell of detect unseen. It is a level 3 divination spell, and the spellbook takes 10 actions to read.
Contents
Generation
Priests may be given a spellbook of detect unseen as one of the two spellbooks in their starting inventory.[1][2][3] Wizards may be given a spellbook of detect unseen as the secondary spellbook in their starting inventory.[4][2]
Spellbooks of detect unseen make up 1⁄50 (2%) of all randomly-generated spellbooks. General stores, second-hand bookstores and rare books stores can stock spellbooks of detect unseen.
Writing a spellbook of detect unseen with a magic marker uses up 15 to 29 charges.
Description
When successfully cast at any skill level in divination spells, the spell of detect unseen has the same effect as zapping a wand of secret door detection, and affects a roughly-circular area in a 8-square radius centered on the hero, displayed in the diagram below.[5][6]
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Within that area, the spell will reveal all undiscovered secret doors and corridors, uncloak mimics, reveal hiding monsters (including submerged sea monsters), reveal traps, and mark the location of any invisible monsters with a I while removing any such markings where no monsters are present[7][8][9][10] The spell's detection can 'penetrate' through clouds on the Plane of Air, and will similarly 'pierce' the water on the Plane of Water.[11] The spell has no effect if the hero is engulfed.[12]
The following information pertains to an upcoming version (NetHack 3.7.0). If this version is now released, please verify that the information below is still accurate, then update the page to incorporate it.
The spell of detect unseen can also detect door traps and container traps, and will additionally display a brief flashing animation at the locations where something was detected—it will then print a message summarizing what was detected, including if nothing was detected.Strategy
The spell of detect unseen has similar use cases to the wand of secret door detection: finding dangerous traps such as polymorph traps and spiked pits, detecting magic portals from roughly the mid-game on, finding the temple entrance in Moloch's Sanctum, and so on. However, the spell is much more difficult to use nearly as frequently—some skill in divination spells will often be required to cast it somewhat reliably, and the hero must also have the energy required, while the wand can be zapped freely, tends to have plenty of charges and is accessible much earlier; many players will opt to keep a spare whenever they need trap detection.
Primary casters and other heroes that aim to cast outside of combat, such as some Monks, Priests and Wizards, may opt to learn and utilize the spell when navigating the dungeon, and other heroes may consider the spell as an alternative if they are saving wands of secret door detection for polypiling. The spell may also be preferred for much more specific builds and conduct play, such as foodless atheists casting the spell to detect traps they do not have the resistances to deal with (or cannot acquire them).
History
The spellbook of detect unseen and its spell first appear in NetHack 1.3d.
Variants
dNetHack
In dNetHack, notdNetHack and notnotdNetHack, drow Healers of both genders can start the game having forgotten the spell of detect unseen.
One of the invoke effects for the Rod of Seven Parts casts both the detect monsters and detect unseen spells simultaneously as if the hero were Skilled in divination spells (having no effect on the latter spell), which uses up 2 points from the artifact's current enchantment and requires a minimum enchantment of -5.
xNetHack
In xNetHack, the spell of detect unseen is lowered to a level 2 divination spell.
Hack'EM
In Hack'EM, the spell of detect unseen is lowered to a level 2 divination spell as in xNetHack.
References
- ↑ src/u_init.c in NetHack 3.6.7, line 107
- ↑ 2.0 2.1 src/u_init.c in NetHack 3.6.7, line 1020: all starting spellbooks have at most level 3 spells
- ↑ src/u_init.c in NetHack 3.6.7, line 1050: no duplicate spellbooks
- ↑ src/u_init.c in NetHack 3.6.7, line 169
- ↑ src/spell.c in NetHack 3.6.7, line 1099: case explicitly calls weffects()
- ↑ src/spell.c in NetHack 3.6.7, line 1137: all spells with wand equivalents (or equivalents in other directional-ized items) fall through to this line
- ↑ src/zap.c in NetHack 3.6.7, line 2165
- ↑ src/detect.c in NetHack 3.6.7, line 1455
- ↑ src/detect.c in NetHack 3.6.7, line 1574
- ↑ src/vision.c in NetHack 3.6.7, line 2747
- ↑ src/vision.c in NetHack 3.6.7, line 2764
- ↑ src/detect.c in NetHack 3.6.7, line 1578
