regarding Optimization module. Yes, the bonuses are great, unfortunately it requires 2 fights to upgrade it & unlock its better bonuses. Those two extra is something you do not want if you aim for minimum number of fights. From this point of view upgrading Magician cowl = 30% magic resist + 20 mana is better since mana management is difficult here.
Baal. his fire attack, which is also not very often does only 500-1000 fire damage. In Baal fight I had two stacks of 268 droids at more than 17000 hitpoints each. So 500-1000 fire damage was not a problem. Yes , archdemons had a chance to cast their halving attack in this battle. That's why they had to be destroyed first (axe of ice gives droids non-retaliation ability). That's also why I kept casting stoneskin on knights & horsemen, so there are more targets for archdemons, since loss of Gilbert units is not an issue here. Also, majority of received damage in this fight was physical, therefore negligible and therefore I could "save" repairs for moments like when being halved.
Jatekos: one fight may be avoidable? both uchkuk and shenobi must be killed in order to enter mirror tower, marquis cannot be moved, the only thing i can think of is kite montero bridge guardian..I think he is unmovable.
From your suggestions : if you read one of my earlier threads, you find out I already managed to get all the way to k'tahu with only investment in Distorsion 1
Hmm. I never played with black knights. I only joined kings bounty community well after The legend and Armored princess were on the market, so once i read they are overpowered i never touched them. But it sound interesting to go for minimum fights with black knights only..