Its fun and really helps but its cheap. In Underpass,head over near the posts and just crouch in the grass.There is like a container thing try going in one of them. My friend did it to me and you can't see them and they can't see you..till you creep out and shoot them.
-Less Cringey Stuff here -
Avy+Sig done by Cyn check out his Shop in the Graphic-Requests Forum if it still exists.