User blog comment:Arbington/Platinum/@comment-3228423-20120718010600/@comment-3325589-20120718095010

The usual desk room tactic of putting a max health decoy in the center of the room and hiding behind it still works acceptably (it got my group to wave 9), but it's easy for even skilled players to screw up and get downed too quickly/frequently for teammates to effectively revive them. The thing that really did us in, though, was getting flanked. It's easy to channel most of the enemies into the stairs or the front/side entry, but you're guaranteed to face phantoms and hunters by the later waves, and they like to sneak around the back. If you don't catch them early, the group ends up pincered and probably dead.

If you can maintain all of that, the biggest concern is hanging onto enough consumables to complete the later waves: medi-gel, obviously, and missiles are necessary for target missions, rooms full of banshees, and big clusters of enemies around the drop-off area for retrieval and escort missions.