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What does "Non-Detection" really do?

diggerbdiggerb Member Posts: 132
I've never found a use for Non-Detection. The spell description is:

By casting this spell, the wizard makes the creature or object touched undetectable by divination spells such as Clairaudience, Clairvoyance, Locate Object, ESP, and detect spells including Invisibility Purge. It also prevents location by such magical items as crystal balls and ESP medallions. It does not affect the Know Alignment spell.

However, I've never known a situation where Clairaudience, Clairvoyance, Locate Object, or ESP has been used by an enemy. Any ideas?



  • GoodSteveGoodSteve Member Posts: 607
    It's used so that when you use improved invisibility it cannot be removed by spells like invisibility purge/see invisibility. Does this happen often: no. Is this spell kinda crappy and situational: yes.

  • LuigirulesLuigirules Member Posts: 415
    Non-Detection doesn't become useful until BG2.

    In that game, every mage and cleric worth their salt will always cast True Seeing if you try to sneak a cloaked character (whether hiding in shadows, or invisible through other means) near them.

    True Seeing is a nasty spell that undoes any illusion for a few minutes after being cast, so it's not really worth it to wait around for it to go away. Especially when they just cast it again.

    Where non-detection really shines is the cloak. Give it to your thief, and they are immune to True Seeing. The spellcaster will keep casting True Seeing, but it won't do anything to you. Then you're free to backstab them to death.

  • szbszb Member Posts: 220
    edited December 2012
    Its a more usefull in BG2, where mages actually cast true sight/detect invisiblity a lot, for bg1 there is not much point.

    EDIT: ninjad by @luigirules

  • MadhaxMadhax Member Posts: 1,416
    Pretty sure that strong demons (Most memorably for me, the one in the Planar Sphere in BG2) can see straight through invisibility. Not sure how Non-Detection affects that ability.

  • The_CheesemanThe_Cheeseman Member Posts: 175
    Madhax said:

    Pretty sure that strong demons (Most memorably for me, the one in the Planar Sphere in BG2) can see straight through invisibility. Not sure how Non-Detection affects that ability.

    It doesn't, they still see you.

  • szbszb Member Posts: 220
    Hmm wonder if blinded demons can see through invisiblity...

  • The_CheesemanThe_Cheeseman Member Posts: 175
    They can if you're within their reduced sight radius.

  • szbszb Member Posts: 220

    They can if you're within their reduced sight radius.

    Too bad, I was hoping it would provide a way to backstab deamons in bg2.

  • and_then_orand_then_or Member Posts: 107
    I'm going to go out on a limb and make a difinitive statement about the final encounter.
    I have the tingly feeling that if I'm wrong, someone just might, maybe, let me know.

    In the final battle of BG1, you can invisibleded a theif and then scout the temple, disarm traps, and plan your am-boo-scad.

    If your invisibleded character is wearing a cloak of non-detection, the dialog will trigger w/ Sarevok, but he and his cronies will not attack. You can continue about your business.

    If you are not wearing the cloak, you are detected and the battle begins.

    IIRC this is also true of the final encouter w/ the demon kinght in Durlags. So there are two instances in BG1 where the cloak has a benefit.

  • TressetTresset Member, Moderator Posts: 7,993
    If you read the anti-illusion spell descriptions carefully you will see that most of them also dispel non-detection. This makes it one of the most worthless spells in the game because it doesn't even function as per its own description or do anything at all really! However the CLOAK can't be dispelled. It is the ONLY thing that TRULY protects you from true seeing (other than immunity to divination)!

  • SharnSharn Member Posts: 188
    I am not sure how well the cloak works, I recall lich's seeing through my rogues stealth while wearing the cloak every time I tried it in BG2.

  • DazzuDazzu Member Posts: 946
    Why would I use stealth for demons when Prot From Evil banes them instead?

  • bbearbbear Member Posts: 1,180
    some enemies have innate abilities that allow them to see through invisibility. Examples are dragons, demons and some liches.

  • TJ_HookerTJ_Hooker Member Posts: 2,438
    I remember reading somewhere that non-detection only works (or works better) for a character using stealth, rather than someone who is invisible due to magic. Don't know if this is true though.

  • ZanathKariashiZanathKariashi Member Posts: 2,867
    Yeah, it doesn't protect spells, unless the spell is generated by an item (rings of invis, staff of the magi, etc). Otherwise it only protects actual stealth skills.

  • TressetTresset Member, Moderator Posts: 7,993
    Like I said before, Non-Detection effectively doesn't work at all. It is instantly removed by all but the weakest of illusion killer spells. The cloak's non-detection can't be removed though and is therefore the only valuable form of the effect.

    The effect of non-detection is to block spells. IIRC it should NOT prevent monsters that can automatically see invisible from doing so.

  • TressetTresset Member, Moderator Posts: 7,993
    edited December 2012
    By the way: I personally think that this is the second worst spell in existance (only infravision is more pointless). If it oh, I don't know, ACTUALLY MADE THINGS NON-DETECTABLE it would actually be useful. As it is; all it really does is cause confusion in players who then make threads like this one to try to figure out what it does. Let me put it to rest now: Unless you want to block the spells "glitterdust", "detect invisibility", and "invisibility purge" it does NOTHING but give you a false sense of security.
    Just remember though: The cloak IS valuable as it blocks ALL illusion killer and invisibility remover spells.
    Edit: This spell (including the cloak) is bypassed by the thief skill.
    Edit Again: Further research reveals that the cloak does not protect spells from illusion killers as per @ZanathKariashi 's post. (which I originally decided to disagree with. How Mr. Heart Eyes knows, I swear, ABSOLUTELY EVERYTHING about the game is beyond me! I am starting to get to the point to where I should just stop arguing with him. If he outsmarts me one more time I will PM him relentlessly until he divulges the source of his ungodly amount of knowledge.)

    (Testing of all these facts was done in BG2. They have been thoroughly researched!)

    Post edited by Tresset on
  • HunterOfBountyHunterOfBounty Member Posts: 38
    There are a few enemy Thieves in BG2 that will use the Detect Illusion ability. I don't know if the cloak protects against this ability, but according to the item description it probably shouldn't.

  • ZanathKariashiZanathKariashi Member Posts: 2,867
    edited December 2012
    Playing the games of the series for 12-ish years, and soloing as every class WITHOUT abusing rest, trap cheese, engine exploits and the like. Though it's not 100%, there are some classes I've only run with once or twice, because they were very 1 dimensional and/or boring (Monks, Beastmasters, stalkers, Wizard Slayers, Archers, Inquisitors, plain druids, shapeshifters). I particularly enjoy mages, rogues of all types, and pure Kensai, so my knowledge of those and their mechanics is always pretty much spot on.

    Unfortunately, it also makes me hate the game to an extent because I also see all the differences, large and small, from PnP and it bugs me a lot.

  • TressetTresset Member, Moderator Posts: 7,993
    @ZanathKariashi Did you ever play anything else in those 12-ish years? Well maybe that's not the issue. Maybe its the fact that I only recently (2-3 years ago) decided to play BG2 and have only done about 2 playthroughs of that. I have enjoyed BG1 though on and off for 12-ish years as well (more like 14-ish come to think of it). I suspect when BG2:EE comes out I will be less the expert I am now and a little more mediocre. I also can be very 1-dimensional with my play style (I'm always good and usually a F/T and usually have the exact same NPCs in my party). I imagine the only reason I am as "expert" as I am is because of my Asperger's; which gives me something of an encyclopedic mind and makes me a quick study for my interests (naturally BG is one of them). Of course such talent comes with a steep price which is primarily my social skills. In any case I have come to respect you quite a bit for your knowledge and I hope you wouldn't mind if I consult you should I have quick questions in the future. As to PnP I have never tried it (due to lack of friends) so I currently have little knowledge/appreciation for it.

  • ZanathKariashiZanathKariashi Member Posts: 2,867
    Aspy's Unite!

    But yes...I'm something of a video game savant, for what it's worth. I love pretty much all games and play them all the time. My collection includes just about every system from an Atari 2600 up to PS3's and 360's. Including some of the more obsure systems like 3DOs, 64DD, Jaguar, Neo-geo AMS, Lynx, several custom handhelds for things like game-cubes, N64s. I also enjoy PC games.

    The only systems I refuse to let be part of my collection is the Wii, Wii-U, DS, and 3DS. I have just about everything else, including several variations of some systems.

    The biggest problems are simply time, and space. I only have room to hook up 5 systems at once, and it's hard to decide what to play given there's only so many hours in the day, and I have to get in my daily exercise routine, meals and squeeze in work as well.

    PnP is pretty fun. I haven't been able to play much recently, since I had barely enough close friends to get a game going, but school, work, families, etc, have pulled things apart, so it's hard to get them all together at once these days. It's pretty fun though if you can make it happen.

  • TressetTresset Member, Moderator Posts: 7,993
    @ZanithKariashi So you are an aspy! I was starting to suspect as much! No wonder you have the edge on me! Heh, my main savant area is animals though since that is my primary interest. But video games does make a close second! We should definitely have a chat some time!

  • PugPugPugPug Member Posts: 560
    edited December 2012
    I seem to recall trying to sneak by some kao-tao with invisibility and non-detection, and it didn't work.

    It seems like there are several elements at work here, and everything is still pretty fuzzy with all the conflicting information in this thread.

    Non-Detection the spell vs. Cloak of Non-Detection
    Stealth vs. magical Invisibility (the spell) vs. magical Invisibility (from an item)
    Divination spells to dispel illusions
    Thief ability Detect Illusion
    Some creatures' innate ability to see through illusions
    Infravision? (haven't seen this mentioned)

    So that's a lot of combinations as to how this might work. Can anyone please clarify?

  • TressetTresset Member, Moderator Posts: 7,993
    edited December 2012
    @PugPug I will address each of your issues:

    1. Spell vs. Cloak: The effect from the spell is removed by illusion killing spells; where as the effect from the cloak can't be removed (only bypassed).

    2. Stealth vs. various invisibilities: Non-detection will not protect invisibility cast from SPELLS against anti-invisibility spells. It will however protect invisibility cast from magical ITEMS and the STEALTH SKILL from effects that would otherwise negate the invisibilities.

    3. Divination spells to dispel illusions: these kinds of spells are what non-detection was made to protect against. It is only effective against those spells which ONLY remove invisibility(glitterdust, detect invisibility, invisibility purge). If a spell removes other illusions as well as invisibility(detect illusions, oracle, true seeing), then it will also remove non-detection if cast by a spell. Non-detection only protects "invisibility" like effects (and furthermore, only invisibilities that come from certain sources; see #2). Spells like mirror image are not protected by non detection.

    4. Thief's detect illusions: The thief skill used to detect illusions always ignores any form of non-detection.

    5. Creatures with the innate ability to see invisible creatures: The ability of certain creatures to see invisible creatures is not affected in any way by any form of non-detection.

    6. Infravision makes things glow red. That's all it does. It, in no way shape or form, impacts the game other than that.

    I hope that sheds some light on this spell. Please let me know if I need to clarify any of my statements or further explain why this spell is pointless.

  • PugPugPugPug Member Posts: 560
    edited December 2012
    I made a spreadsheet to make it easier. Is it correct?


    EDIT: I forgot creatures that can see through invisibility. I assume you aren't revealed, but they attack you. Can these creatures also see through Stealth?

  • ZanathKariashiZanathKariashi Member Posts: 2,867
    edited December 2012
    Untrue, the thief's DI IS negated by the cloak of non-dection. DI has the exact same properties as true sight (except the success chance per illusion per round is equal to your DI skill level), except it's not a spell. This can be tested easily by going to the planar prison, the halfling thief there spams 100 skill DI constantly if anyone is stealthed or invisible. Normally it reveals everyone immediately, but wearing the cloak of non-detection, while being invisible via an item or stealth protects against it (but not spell based invisibility) and you can actually reveal him if you're invisible via a item and using detect traps yourself with high DI).

    Yeah, Kuo-tua are innately able to see through any form of stealth or invisibility (but unlike most other creatures like that can still be backstabbed, if you're willing to set it up).

    And yes vs those creatures, your stealth/invis isn't dispelled, they simply ignore it. Other creatures that might be present remain unable to see you until something drops you from hiding/invisibility.

    Invisibility specifically mentions it foils infravision. All it does is allow you to see heat signatures in dark areas, though technically, it SHOULD reveal stealth, unless the hider is wearing a cloak of non-detection or under the effects of the spell or taking measures to specifically foil infravision (covering themselves in cold mud, etc).

  • SpaceInvaderSpaceInvader Member Posts: 2,125
    Try to use it vs Gamaz, he will get mad. lol

  • TressetTresset Member, Moderator Posts: 7,993
    edited December 2012
    @ZanathKariashi What you said about DI... I did test that in the pocket plane. I made Cernd wear the cloak and made him invisible with a ring (ordinary sandthief ring found in BG2) and booted him from the party. Then I made him mad with a skulltrap from Aerie. Then I sent Jan in while invisible with the staff of magi and detecting with 100% in his DI skill. Cernd got revealed. All this was done without Cernd seeing any of my party. I made sure he didn't attack me. Unless the AI will automatically switch cloaks DI does bypass the cloak. Was there any flaw in my test? If so I will correct my previous statement...
    Edit: What is the creature ID code for that thief in the prison you mentioned? I would love to use that to test...
    Further Edit: @ZanathKariashi Wait... I remember there being a yuan-ti mage in the planar prision. Yeah! He casts true seeing too! I remember clearly now! Perhaps you were mistaken about the source of the illusion remover? Or did you take that yuan-ti out first and then test?

  • ZanathKariashiZanathKariashi Member Posts: 2,867
    edited December 2012
    Nah, you can actually SEE the thief attempting to use the DI, and it happens immediately the instant your party warps in, before the Yuan-ti can even finish casting truesight. And the point is, it's irrevelant because my character isn't revealed until I decide to make an atttack even with truesight AND the DI going every round.


    Though bare in mind, in the unmodded game only 2 thieves in the whole game will use DI against you (the prison one, and the one in that adventurer group in the underdark), the rest, like those rune assassins can simply see through illusions by default (but don't dispel them), or not at all.

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