The abilities your hunter has can be used in the field to help you locate and trap survivors. Hell Ember is the hunter you'll start with, and his first ability are puppets you can place in the field which will surveil the area, and highlight any survivors that run through their line of sight. You even get more puppets as you go. Other hunters of course have other abilities. You can check each hunter and their abilities from the Witness Record so you can plan your strategy ahead of battle.