I think this looks really interesting, getting some nice F.E.A.R-vibes from this. 
I also enjoy that it is not simply a good vs evil-thing, order vs chaos is a lot more interesting and it really helps the setting that we have magic users in the GRAM and the mention of witches out in the world having established societies. 

However, magic is described as extremely powerful, a basic "do anything"-ability but with the fickle-rule applied to it. So I am wondering about exactly what a trooper (non-magic user) can do against a witch?