Genjutsu within the NV are illusionary techniques which require handseals and chakra similar to ninjutsu. They do not cause physical harm but rather manipulate the flow of chakra to the target's brain, causing a disruption of the senses. Personally I don't really see myself using genjutsu in battle, it's just doesn't seem like it'll fit into my fighting style. In any case, genjutsu within our RP has a strict set of rules and guidelines that must be followed, specifically referring to how to break out of the illusion, how to properly recognize when one's been caught within one, etc. That's about all I know.