I'm playing Batman: Arkham Origins and one of the tasks for me now is:
Get at least an A grade in a fight with at least high difficulty
I tried it a lot, got in a few fights that were Extreme difficulty and won it without getting hit(other times just once or twice). But still the max I was getting was Rank B. With Low difficulty I sometimes manage to get Rank A and once I got Rank S with one of the predator encounters.
So the question is: how is rank calculated and how can I get at least Rank A in a fight with at least High difficulty?