I got this trophy accidentally. Wait till its night time, from the main safe house, theres a back entrance/exit. Go out there and make noise for the Volatile to come after you. Dont go away from the safe house, so stay close to the door. once the monster comes, stay inside the safehouse until it comes storming at you (he wont enter) it will then jump backward towards a burning barrel with spikes in it. Use your UV light to force it into the barrel and it will die immediately.