Unlocking all the heroes u "missed"?

I'm pretty sure i've read somewhere about the possibility to unlock all the heroes u still miss once u completed the game.
I mean, during the storyline u have to choose, for example, between margrid and master of whispers. tho not having whispers guy prevent u from starting 2 coops so u have to rely on other ppl's master of whispers, aswell as u cant start dasha vestibule without margrid.

i dont really care about not being able to play those missions again and again whenever i want, once i mastered them i'd play them just for fun noone forces me, but i kinda live the idea of having all heroes

After beating the game i see noone that gives me such an "unlock all heroes option"...
can someone confirm that it exist? and found where? anything at all?

When you finish the game you walk a fairly long path, and along that path all heroes will stand next to it. If you didn't unlock any of them it'll show a quest ! mark that gives you a 2.5k exp quest to unlock them. It's nothing big, just "talk to this guy to unlock me".

2.5k exp, new hero. Easy.

Only hero you wont get from the end is razah, people have not yet come across how you get him and if they do know they are not telling.

What most people dont understand about the 16th hero. YOU ARE THE 16TH HERO. I dont understand about Razah. I think its just to add Suspence to the game . Which it sure has. I would still like to Explore more about this.

If I am the 16th hero, when do I get the option to choose to be a demon? This is also stated in the manual.

'It has the knowledge and capabilities of a normal human being, but lacks the common sense'
I doubt it that Anet would be insulting their own customers.
And stop this rumour, since its only based on ONE interpretation of a single line in the manual. Might as well go interpret evey single line in the Bible, Koran or whatever religious text and use it for your own purpose... oh wait, people already did that. DONT LISTEN TO INTERPRETATIONS, they are not the TRUE and ONLY way of reading something. Make up your own mind, think, rationality FTW!