Spellbook of invisibility

spellbook of +   invisibility
Appearance	random
Abundance	2.54%
Base price	400 zm
Weight	50
Turns to read	15
Ink to write	20–39
Spell type	escape
Level	4
Power cost	20 Pw
Direction	non-directional
Equivalent	potion of invisibility
Special for	ranger

In NetHack, the spellbook of invisibility allows you to learn the spell of invisibility. It is a level 4 escape spell, and the spellbook takes roughly 15 turns to read. It is the special spell for Rangers.

Generation

There is a ~2.54% chance that a randomly generated spellbook is a spellbook of invisibility.

There is a guaranteed spellbook of invisibility generated in a chest on the middle level of Vlad's Tower.

Effects

Casting this spell at any skill level causes you to turn invisible for 31 to 45 (more) turns.

Strategy

This spell might be useful if you only want temporary invisibility so you can still enter shops later on. However, there are other sources of both temporary and permanent invisibility (e.g. via wand, ring, cloak, or potion) that are more convenient; at worst, if you are permanently invisible in a way that cannot be undone, you can still enter shops using a mummy wrapping or teleportation. Such permanent invisibility is often easier to obtain than the spell itself, and Rangers in particular are very unlikely to be able to make use of this spell before they find a mummy wrapping.

One niche use for this spell is to cast it before eating a stalker corpse to make the invisibility permanent and gain the see invisible intrinsic - but even then, other methods for this niche are more available in comparison to the spell, to say nothing of having a ring or cloak that can ideally be worn and removed at will.

Variants

Some variants focus on making the spell of invisibility more viable.

SLASH'EM

In SLASH'EM, the spell of invisibility is moved to the newly-added list of body spells (where it is still a fourth-level spell).

dNetHack

In dNetHack, the Windowless Tower has a spellbook of invisibility in the same place as Vlad the Impaler's original dwelling. Invisibility is also one of the spells that can take advantage of spell maintenance.

FIQHack

In FIQHack, invisibility is also a spell that can be maintained and kept in effect.

xNetHack

In xNetHack, the spellbook of invisibility is no longer randomly generated, but can still be written or wished for. It is now a level 1 escape spell, making it far easier to write and cast, and permanent invisibility is also no longer available as an intrinsic (though extrinsic sources are unchanged). This gives the spell much more of a use case compared to vanilla NetHack.

EvilHack

In EvilHack, the spell of invisibility is lowered to a level 3 escape spell, making it more feasible for Rangers and some other roles to utilize; this also makes the spellbook an eligible candidate for generation as part of a Wizard's starting inventory.