After reading Aatrox' lore again, I've thought about something. Before the Institute and the League were formed, Summoners were the leaders of armies and figureheads of their political organizations, and were the ones that brought down the heavy magical assault.

It seems pretty likely that the Magelords would be the original all-powerful Summoners. Their names support that, as well. It also seems like they weren't the "good guys". Maybe the Protectorate was defending the world from their magic-fueled ambition and thirst for power?

So maybe Aatrox is actually participating in conflict as long as history itself to stop the legacy of his greatest foe from being the greatest authority in all of Valoran?
#conspiracy

But hang on, that would have been a LONG time ago. And the League was formed after 3 Rune Wars, the third of which was presumably in recent times. So while they may have been powerful summoners, they wouldn't have been responsible for all the magical wars.

I still think Xelnath knows the full story. He is the right hand of the Witchlords, after all.