In Mission 3: Embedded — Objective: Get Through Building (early in the mission), you will reach a place where Farah (girl you are walking with) goes to the right and you must go left where the workers are and collect a cinder block. This is an unmissable story part, as you need to pick up the cinder block to get past the guards (they will think you are one of the workers). Take that same cinder block to the end of the mission. You are allowed to drop the block in every enemy section. You can shoot any enemies in your way. Then, before moving onto the next objective, remember to take the cinder block with you. Also, make sure you do not confuse it with other cinder blocks sitting on the floor. It is recommended to put it in memorable places where there are no other blocks. You can combine this achievement with the “Play Dead” achievement, which also takes place in this mission.