After the quest "Blood Run" you will notice a red quest marker right outside where you are leaving. Go talk to the Messenger and he will give you a letter, which will start the quest "Turn and Face The Strange". Complete the quest and it will unlock the mutations system. Once unlocked you will at least 2 ability points and 2 of either a Greater Blue, Red or Green mutagen to unlock one of the abilities. Pick one that you like, research it and the trophy will unlock.