When in co-op play, and your about to just a small ledge, let player 2 or player 1 jump up and put the shield projector on the player on the ledge. Let the player with the shield around them tear the enemies up, then continue on. When you both have low health, hide somewhere, then let one player die. You do not die. 1 must stay alive.
Then when 1 player is dead, he hides, then the other one that hasnt died yet goes out and gets their head blown off. then you both have full health.tadaaa.note: if you both die, game over.