I was thinking about Shadow Magic, and I thought that, (this is my PERSONAL opinion), it’s main problem for me was it’s effect, which I find pretty lame, just become color-blind isn’t a big problem while Light Magic actually annoys your vision. So I was thinking for a better effect it could have and I thought of this : Terrorised. The Terrorised effect would either give you low Insanity, weaken your Warding or just increase you chances of becoming insane. The reasoning behind this is that the effect is named Insanity and fear makes your insane sometimes. And Shadow/Darkness is one of humans most elementary fears.
Increasing/inducing insanity seems like it’s way too overpowered to be a mechanic for a base magic imo, especially on a magic like Shadow which already has really good stats. I can see ink’s status effect being repurposed to shadow as a vision obscurer rather than just colour-blindness; but like I said shadow’s still a good magic without status effects and it would probably need to be rebalanced if it got one.
A status effect that gives the opponent insanity might be cool for a rare magic like darkness or death, with some sort of downside. Death is supposed to have “only forbidden and cursed spell types”; Forbidden spells increase the user’s insanity by 1, and Cursed has drawback (I believe drawback is self-inflicted damage) so it might be balanced if the user can give its opponent a bit of insanity as well
You’re right on the fact that it would be overpowered, but maybe Vetex could make an Ancient Magic called Mind Magic that has this effect