Invisibility

[Stridey]

Not something I ever really used to use back in the day when I played it on Amiga.

I noticed they still attack, so I'm assuming at this point it decreases their chance to hit?

[Ameena]

I don't know - I never bothered with it either . Fireballs are about the only Wizzy spell I use.

[terkio]

I had no success with invisibility.
I think it does not work, so forgot about using this spell.
Same about darkness, it does darken but I found no use for it like hiding in the dark.
It seems there is no way to trick monsters with invisibility and darkness.

[ChristopheF]

I never used the Invisibility spell much. We'll all agree that the game is more about killing all the creatures on our path rather than sneaking around.
But invisibility does have an effect as verified in the source code... but not exactly the same depending on the version of the game that you are playing.

In all versions, some creatures can 'See invisible' (list here: http://dmweb.free.fr/?q=node/1363 ), so they completely ignore that the party is invisible.

In the older versions DM for Atari ST, Amiga versions 2.x, Apple IIGS, PC-9801, FM-Towns, X68000 and in CSB for Atari ST:
If you are invisible and a creature doesn't 'See invisible', it won't see you at all so it will not move toward you and/or attack you. This applies even if you are adjacent to the creature.

In newer versions DM for PC, Amiga 3.6 and in CSB for Amiga, PC-9801, FM-Towns, X68000:
If you are invisible and a creature doesn't 'See invisible', its ability to see you ('Sight Range') is decreased by 10, which is enough to counter the highest 'Sight Range' value used by Wizard Eye / Flying Eye. However, if you are adjacent to the creature then there is a random chance that it will still detect you.
A second effect is that the probability of creatures hitting you is reduced when the party is invisible as well as if the creature does not have 'Night vision' and the light level in the dungeon is low (the darker the dungeon is, the smaller chance you get of being hit).

[Ameena]

You'd think all the creatures in the dungeon would have night vision (or have no reliance on sight at all, having tremorsense or whatever instead), seeing how with the exception of the Hall of Champions (where none of the monsters go anyway), the entire place is completely dark unless a party wanders by .

[slickrcbd]

Not to mention that the invisibility would have limited effectiveness since the party has a moving light source. That alone would tip the monsters off that something is amiss and make them come to investigate.

[Erik Bauer]

Never used Invisibility or Darkness spells.
I tried them a couple of time on the first playtrough but with little to no result

[Saumun]

I don’t recall ever bothering with it either, but it’s weird to learn how it works after all this time.
According to the chart in the link Christophe provided, it should work on anything except rives, black flames, and Chaos (provided you’re using an old enough version).

[Ameena]

You'd think the list of does-not-work creatures would be much longer - I mean, plenty of things don't even have discernible eyes, such as Rock Monsters or Purple Worms...