I sincerely apologize, but the single-player campaign should either adhere to established facts or explicitly state that it presents an alternate history. In "Flame of Vengeance," the author mentioned that Biara does not die. In the maps for the future campaign, I also offer a different take on the story, but I mention this at least in the messages within the map. However, here, Zehir kills Biara. It's definitely unexpected. Biara was killed by Isabel.
I can also note the complete absence of scripting. For a single-player campaign, I think this is unacceptable. But that's just my personal opinion.
Finally, "We have nothing, but everyone else has dragons." I personally experience a total facepalm when I see a level 7 monster guarding a precious resource mine.
I apologize if I'm being too harsh – you are still improving in design. I'm not perfect either, far from it.
Sincerely.