Heavy Fire: Afghanistan

If you don't earn this trophy naturally while playing through the game, wait until you are done you two main playthroughs (Rookie and Veteran) and then re-play the first mission (Operation 1 - At Scene) on Rookie difficulty. Once you get to the last wave of enemies in the level, let them shoot you until you get down to one bar of health, and then kill them to finish the level. See the following video guide: