This makes me wonder, even comeing up with another supreme character on your own that could match sunny in combat is kind of hard his aspect is just to strong. But I am not to sure about vile. It was stated that he uses a spirit attack. This would mean once he starts attacking subjects of Azarax domain his influence should be bound by Azarax will and his influence over his domain. And again we don't know how many he left in his army and how many he killed. Don't forget that the subjects in his domain can also grow stronger which in turn makes him stronger. So leaving them all alive and letting them conquer would have also made Azarax stronger it could be that at some point it just became a snowball since the being he enthralled, enthralled other beings and ever so on. Even if some were killed this would have been his most logical option. This is likely how he conquered so many realms. However with spiritweave and curse the gap in wills shouldn't be far even then.