((( Must be on co-op to complete.))) First each of u gets three thousand then one of u must prone right in front of the mystery box and grenade urself. The other player must open the mystery box and wait until right before the very last gun or the last gun to revive ur partner. Right after u revive ur partner press (x) very quickly then right after u press it press it again and hold it u should have the ray gun, the deployer, and some other guns and maybe a flamethrower. And dont get frustrated it may take you a few trys to do it. It took me a couple. Good luck!!