You have to choose from a random contract or if there is an option to pick one, from the main menu. Once you are in game, you find 3 clues as to where the boss's location is at. Once you find it and kill it, you have to banish it. Once you have that at 100%, you pick up the bounty off of it, and book it for an extraction area. These are located on the sides of the map with two arrows pointing to a center. Also once you have a bounty, you are able to use it to see enemy players if they are close by. Beware you only have a limited amount of uses to do this though.
Once you extract with the bounty, the achievement should pop!
