Your karma rank is determined by the gauge next to your charge meter. Positive karma is sorted into three separate ranks:
Guardian > Champion > Hero
Doing anything that’s considered good, such as completing the blue side missions, doing stunts listed in blue (arc restraining, healing civilians), etc., will move your karma to the positive side. As soon as you’ve reach full positive karma, the trophy will automatically unlock.
- Side Missions that results in earning Good Karma
Reaching full Hero rank will NOT lock you in this rank; you'll still have to worry about your karma moving back towards the bad side. So unfortunately, you're not free to cause as much collateral damage as you want and still be treated as a hero among the city.