19. What is the highest level your hero can reach?

There are actually 2 answers to this question, but they are both similar – there is no level limit!
Your persistent Warlord character can go as high as you like. Once he has reached about level 60 though, the increase in power beyond that is very small

Heroes and other troops in the game can also level up, but once they get past about level 12, it gets harder and harder for them to gain levels.