- You wiped out four Taken with a single flare.
Obviously, the first thing to do is to get a flare gun. Once you have a flare gun, you will need to be in a situation against many Taken. One of the best places is at the Bright Falls helipad in The Clicker, as many Taken flock towards you. Just force them to bunch up and shoot into the crowd, hopefully killing four or more of them. This will unlock the achievement.