In my Aeneas campaign the requisite to unlock the Heracles voice y just raise Aeneas to level 25, but in my Campaign because I do some quest at the same time (combined with a seer quest) Aeneas jumped from level 24 to 26 and the stygian voice of Heracles was not unlocked...
I don't know if is a reported bug already,, i have screenshot for aeneas lvl 27 and the not unlocked voice of Heracles but i dont know if is necesary upload it.
Another weird finds that I know is that you con go solo with a hero to a door and he can destroy the door without represalies from the defense.
Also if you use a scale with you hero in a wall, it will dissapear or die, he just vanish...
I think that are already reported bugs but I dont have the time to read all the forum, really sorry if I make to lose your time.