[@Omni5876][@TheMerlin]: Ferezanthe was a storyteller/bard not a Hero. 
But the Firemage I named Tourmaline and stated that he did fight the Sorcerer king. 
So technically that would make it 11 heroes. 
11 btw is a Masternumber related to Karma. 
The Number 12 is actually a representation of authority and perfection. This number can also represent the church and faith in general. It can be also used as a symbol of divine rule, actually the symbol of the perfect government of God. It also stands for polarities as it is made up from the number 1 & 2. 
However it could be said that all the numbers are important in one way or another. So if you want to pick a number for its symbolism look into that. 

Since we are talking about war we also have to talk about propaganda. Not everything recorded or written down is truly what happened. After all only victors write history. Or in these days rewrite, falsehoods for the greater good or stories that were hushed up. If you want an example 'the holocaust' still is debated by some up until this day. Regardless on where you stand, this was not even a 100 years ago.
Meaning something as devasting as this would have allowed a lot of room (to create a new narrative-story for the kids to learn).
We can safely say all those involved in that epic battle are dead. (Whether in the battle itself, the cataclysm that followed or later of old age).
Considering this was a cataclysmic event that caused the destruction of nearly the entire planet we can also safely say a lot of things written, would either be thing that were written long after the events or passed on the old fashioned way; (hearsay) mouth to mouth. 

My made up writer Ferezanthe and my scholar Folken were just stuff I threw in to make this world feel alive. After all a world with its small references to writers or games gives hints of culture and a more realistic feel.
So this is what I had in my head when the two were conjured up: 
 Folken is of a time way before the cataclysm and more or less droned into the heads of nobleman and scholar alike much like Confusius was. 
Whether friend or foe he is known and more or less study material much like some of our famous ones are. I mean we all have heard of Nietzsche, Sartre and Confusius, we might not even know their quotes, but we know who they were. 
 Ferezanthe and the many tales that sprang from this particular writer and storyteller was possible because there was more then one; 
Much like sons being named after their fathers or paintings being mistaken as works done by the master himself, whilst infact they were done by his pupils. 
In this case The name Ferezanthe just gets most of the credit.
This also allows us to play with the mindset that Arn and Eilis undoubtedly will come accross in the discussion of the Sorcerer King's depiction. 
Arn would have known the stories told by the Belisian's about the powerhungry Warlord going off his rocker, as Eilis would be telling Arn how mistaken he is and how the Sorcerer King was brutally murdered and thus the heavens came crashing down* (just as an example)
A conversation I can't wait to get to as it would mean we will get to flesh out the stories and the real events of what has come to pass.

Why is this important?
Well I think this war, even if it were just for rescources is to Vaim more then just that. They were getting to their peak once, only being stopped and forced to tighten their belts once more due to their big rival screwing up their plans. 
Not only that, but their King and hope for a more glorious future and better lives was stopped and with it the whole event caused such destruction that it nearly blew up the entire planet.
So I would say Vaim's reasoning and attacks would be also filled with 'payback is a bitch' mentality. Assume these are potential sons, daughters, grandsons and granddaughters that have a bone pick with Belisio.

That being said here's a quote from Confucius that I found apt: 
“Before you embark on a journey of revenge, dig two graves.” ― Confucius

Do you [@TheMerlin] now have an idea where we are ultimately headed with this? I mean playing out battles is fine, but eventually you're going to have to flip a coin on whether or not Belisio will fall. (Personally from a writer's point I gleefully shout yes, as I love a good dose of utter horror and drama) but it would allow for us to go into a sort of resistance storyline, first fleeing and desperately having to try and reconquer the kingdom or attempt to coup through assassination. So many potentials for plot and possibilies...
I don't need a who or how, I just wondered if you made a decision regarding that.

Anyway I have ranted long enough...I'll think on certain things some more. Oh and [@TheMerlin] I hope you'll write Leo's reponse as well.