First, regarding the commentary: replay the Necromancer campaign. There, Markel says, "My teacher, Sandro, was the greatest mage until the fanatics of Helgi killed him..."
Second, can you post the story you've come up with in its entirety somewhere? It's impossible to read it like this.
Third, if you have a complete story, I can write a review for you (with comments on how to improve it). Right now, what I've read seems too far-fetched, especially regarding the Elves. ;)
And I want to draw your attention to an interesting fact. Read the official history on the Nival website:
"The Wars of the Ancients - The Angels launch a campaign against the Faceless Ones. The destruction is terrible, and the oldest races suffer greatly in the war. Early Elven civilizations and kingdoms are destroyed. The original Dragons become a myth and are gradually forgotten. Peoples worship only the Elemental Dragons."
Couldn't this have been the Armageddon? Legends may distort events, names, and titles, but they can't ignore a global change in the world. :)
That's where you should start, in my opinion. In your story, you're using the history of the third game too much, forgetting about the fifth. You're kind of forcing the fifth game onto the third, when you should be fitting the third game into the fifth. Well, you get the idea. Your story should be such that everyone says, "That definitely explains why things are the way they are in the fifth game!" Instead, you're getting, "Well, everything in the fifth game is a lie; it all came from the third game..." It's just my opinion, but think about it. I'm all for this project, but unfortunately, time is running out. Maybe I'll come up with some more ideas. ;)
Best regards, Supreme!