You can throw stones by pressing . The enemy will be fully distracted when he walks to the location where the stone landed. Do this to 25 different enemies. This trophy should come naturally while playing through the main story because there are some stealth missions where you are not allowed to get detected. Throwing stones makes it easy to sneak past enemies. You can also farm the 25 distractions at outposts. After liberating all outposts there are still enemies at the coordinates X: 412.4, Y: 729.5. Some people have reported that they needed much more than 25 distractions. Don't worry, the trophy is not bugged. Just keep distracting enemies and it will unlock sooner or later.