Kill a Dragon with the Bow
One of the Garrisons located in the north west part of the map has a Blood Dragon standing outside the entrance. This is the easiest place to get the trophy. All you have to do is lower the Dragons health until it has a tiny amount left, then keep shooting it with the bow. The bow does very little damage to the Blood Dragon, but for maximum effectiveness, shoot the Dragons purple chest when he rears up. As soon as you land the killing blow with the bow, the trophy will unlock.