Which Haven heroes do you prefer?

And Vittorio has really powerful ones... There's already such a powerful ballista there... May God help you.

Yes, a ballista with an attack of 30+, of course, especially with fire arrows. A difference of 30 in attack increases the damage by 2.5 times. However, in the late game, it's much easier to destroy a ballista. Many cities have creatures that attack more than one cell, meaning you can simply target it with someone without wasting a turn. Although, in an extreme situation, you can spend a turn on it.