Caverns Proximity Trap of Death:
I have 2 very easy kill tricks in multiplayer, even with the +10 health on. The two easiest levels are the bunker and caverns. First memorize the starting locations, like where you start after you get killed. In the caverns:
In that little room with the elevator
Next to all those metal boxes and oil barrels
On the top deck where the armor is
To set the ultimate trap first get 11 proximity mines, from the room not the lower deck, go on the lower deck and line them on the bottom of the upper deck (look up with "C" and throw em, but far enough so they won't explode while you throw them). The other player also cant shoot them this way. As you go along the bottom deck, you will pick up the other two boxes of proximity mines. Go into the room with the oil barrels and boxes. Throw three mines (one on the back wall and two on the front boxes, on either side of entry. Then with your other 8 mines, go down the large hallway, and turn left to go to the elevator room. There should be a circular blue hallway with lighs on both sides. At the end of the hallway stop. Now turn to your right, and throw a mine on the light or somewhat near it. Now move forward a section. Turn around and throw one on the light again. Repeat these steps until you get to the other end of the hallway. Go out the big door and close it behind you. Throw two mines on the closed door, just in case they survived the hallway. Go to a safe place, and now you have all of your traps set.
Bunker Proximity Trap of Death:
Again the first step is memorizing the start places. They are:
First Jail Cell: The best place to set your trap is the jail cell, the door to outside (there's no esccape for these two!), and the room with the Assaualt Rifle in it. The first and easiest one to set is the jail cell. Open the door throw three mines in a good place and leave. Trapped in room of fire. How horrible.
Door to Outside: Just throw some on the long hallway but seperated enough so they don't blow up together. Like four or five down the entire hallway, and one on the glass doors.
Next to the Remote Mines in the TV Room: This isn't one of the better places to set your mine traps, because it cuts off your supply, and because it's an open area, but if you want to you can.
Next to the Assault Rifle: There is a room with a Assault Rifle and two boxes of ammo in it. Throw two mines in the room and one just out side the door, just don't walk past it, or your in for a surprise.
Next to ZMG 9mm: Like the room with the Assault Rifle, there is also a room with a ZMG and two boxes of ammo. Throw one near the door , and one outside the door