I only added damage reduction, I mean the part where attack increases if attack is
much more than defense, and vise versa. I think it's a decent and balanced concept, in general if attack is 100 times more than defense then attack = attack*3. And with super high defense attack goes closer to 0 (but never reaches it).
I'm still trying to implement different formulas after that part to see which one is better.
Btw if you still test it vs the goblins pack, it's not a good idea, their stats are low even at high levels. I test it vs lvl100 Warrior character.
As for dodging magic, I don't see a problem with dodging non group spells. I just don't know how to check if the spell is a group one