[@shylarah] The main point I wanted to stress was that individual warbands are honed to operate together. They are encouraged to compete against other warbands during training exercises. It's an iron sharpens iron mentality. 

Also, due to them having unique magical abilities, each warband is an individual case and so the curriculum that's taught differs with each group. We can increase the rate at which different groups share the same space (probably during Gregoroth's general combat sessions) but I don't want it to be a daily thing. Maybe some of the senior warbands are tasked with prefect duties and are allowed within the different compounds. This is probably how Magnus was able to do the kind of things he did.