I just beat lvl 100! I had my rogue with lvl 100 stun and max speed, this combo only allowed the boss to attack twice at the beginning, but was stunned the rest of the battle... Probably need to change the max level for the stun upgrades.
I like this game. The only thing I could think to make any improvements would be to make the characters change equipment based on upgrade level, i.e. warrior sword would change each 10 levels of attack, and helmet would be attached to criticals. in the end you would have an epic knight with dragon/demon equipment...
fixed!