Shadow Warrior

Lesser demons which have been participating in combat with you for a long time without being killed will eventually transform into enraged demons. This transformation is easily observable as they raise into the air and are surrounded by lightning, before falling back to the ground again and are coloured much darker, move faster and deal more damage. Kill 50 different demons in this enraged state to unlock the trophy. You should not need to farm this trophy, it will likely come naturally as you play through the story.