Demon invasion.

You're wrong to dismiss it; everything is actually quite doable on Warrior, moderately difficult and fairly interesting. I only managed to lose the 5th one on my first try, and I play all Master Campaigns on Warrior for the first time.

Now, Hero is a different story: the second one is very hard, I can only imagine the 5th, and I'm also afraid of the 4th, considering there are several enemies and they roam together, the mentor's guard is strong, and handling defense and the mentor (as well as darkness, machines, and attack) simultaneously without the help of a mind-controller is problematic. Only two cities (the second without dogs) and a guild limit of 3/2 (which allows giving up darkness magic before the mentor if a bad skill is offered for a level), because the value of darkness magic at that stage is only in Mind Control and nowhere else. (But there is a town portal scroll lying around and 2 pairs of boots, which is quite useful)