Get on high roof and fenced off area on "Calypso Casino"
A friend/squad member on the multi-player map Calypso Casino is required for this glitch. Make your way up the stairs toward the helipad where you must bring the Intel to on an attack and defend mission. At the top of the stairs there are two boxes overlooking the top floor where you can take cover behind. Go to the very first box closest to the stairs. Press Cover about two or three times at the right corner of the box, then hold Cover. You should now be floating in the air. Do not move until your friend runs up behind you and runs into your back. While your teammate runs into you, start pressing Forward and he will "push" you on top of the box. Now that you are on top of the boxes, there should be a railing next to you. Walk onto the railing, then run towards the stairs and the railing should lead you around a previously fenced off area where you can drop down into and cover all three entrances to the helipad if your team is defending the Intel on the helipad. To proceed, keep running on the railing past the fenced off area. You should be running towards the roof that connects with the elevator building. Run to the very end of the railing then run onto the roof. You now have complete coverage of the entire roof area of the map. You should watch the repels or elevator door if you have an SMG/rifle, or watch the far repel if you have a sniper rifle. If you have a shotgun do not bother going up there.