Loki Fenrisulf IV said:
But the thing is, the goal of this genjutsu is to convince the person that something is wrong. And if the person suspects there is something wrong but they can't point what, their first guess is genjutsu. They don't need to be a sensor to believe they are being affected by a genjutsu, just believe that something is wrong and see nothing. And there goes the genjutsu that makes them think something is wrong.
To make this stick you either need to recast it every time or layer it so much they convince themselves it isn't a genjutsu before the layers run out, and at that point it is just not worthy. The first option because using so many times will make them look for threats - if they believe they are in danger and it is not hidden by an illusion, they will try to find said danger to either deal with it or escape - and you'd be a sitting duck because you can't just escape else it wouldn't be recast. The second... it would be easier to use other, more useful and/or subtle genjutsu, unless this is so easy and chackra-efficient it compensates that much layering.
I'm not saying I dislike the idea, just the only two ways I see it as being usable are flawed. Unless it was a poison or seal instead of a jutsu to be cast, or somehow harder to dispel than usual genjutsu somehow.
Personally, this makes me remember an episode of Mission: Impossible, where a target was successfully driven into a paranoid frenzy in order to make him shoot dead another man, while the police were just about to knock on his door.
Imagine it being used on a guard of a hard-to-reach businessman, make him think something's going on. Sure, he thinks it's the job, perhaps stress. Then he or one of his boss's "employees" starts "finding" little clues to further back up that unnameable feeling. A receipt at a restaurant his wife works at left out on the boss's table. A cufflink in his wife's coat pocket.
Stir up that pot, and you're going to get some fireworks. Especially if an anonymous picture of the guard's wife kissing the business man in a location where they both happened to be at one time, and conveniently "disappeared" for a touch too long at the same time. Angry, hurt, betrayed, he goes to confront his wife, only to learn a horrible truth -- business man has been forcing her to have sex with him to save the guard's job. Now he goes into a rage, finds his boss, they have a showdown, he loses it in the face of all the denial and kills him. Worse-case scenario, guard dies, businessman replaces him with a much more stable security member, and a few days later, businessman keels over and dies from a heart attack -- should have listened to the doc about
oversalting his food.
Hard to reach target now dead, grieving wife has no idea what came over her husband, and all the evidence of any misdeeds to link anything mysteriously disappears.
atlas_hugged said:
While we're on genjustu, what about examples of genjutsu that would be dangerous or undesirable enough to be in the Forbidden Scroll?
No real idea, to be honest -- if anything, I'd assume any sort of genjutsu designed to drive a person crazy, like the Malkavian clan's special discipline, Dementation. And speaking of VtM, I'd furthermore say anything that a Chimestry level above 6 could produce might warrant some forbidden time as well.