Quick battle.

I don't understand, are you talking about auto-battle or quick battle? Anyway, I haven't noticed the former in this part of Heroes. And I don't use the latter because I need to level up my karma.

What do you mean, you haven't noticed it? In the lower right corner, next to the "Hero's Special Attack" circle, there's a small "Automatic Battle" circle. Click it, and it will do its thing.