This trophy/achievement is only in the original version of the game and not in the Definitive Edition. In the Gallopolis section, you will receive a crossbow, which you can use to strike enemies to make them come towards you. However, there is a lengthy sidequest that involves hitting hidden targets in multiple areas of the game. Each of those areas tends to have five targets, after which, you can report to a specific NPC to get a reward. To see the locations of all targets you need for this, visit the Crossbow Kid section of the game.