I just beat the last guy on hard mode 3 and I have to say he was nearly impossible. Over 100 attack power and
0+ def made all but two of my characters useless against him. Touka and Karura both having maxed attack hit him for only 200-250 damage each time. touka and karura's combos did around 1000 damage and both used their combos a total of 17 times before the bosses health got below a 1000. in addition theres the last bosses double attacks that wipe out every one who wasn't touka or karura, and touka died half way threw this fight.
I' dont know were I'm going with this, but how much harder can this possibly be on hard 5? Karura was rapidly approaching his level (level 64) and if he had more hitpoints I probley wouldn't of been able to keep leveling against him every other attack, and if he had anymore attack power he would one shot all of my people in his first attack.