There is an area under a set of stairs this week you can hide under to avoid enemy fire(although it's possible for a phalanx to drop in their to, if you can aggro the boss into the stairs there are sections of it you can shoot through to hit him

Still its not hard to deal with the phalanx in the Hole if you have 3 people as you can just panic gangbang him. (Very surprising the first time it happened to my team though haha)

Just thought I'd share some info as to how to complete this week's nightfall. Did it last night without too much trouble after we figured out how to approach the strike boss without getting our shit pushed in: As soon as you enter the room with the strike boss (Valus something or whatever his name is) move to the left side of the room. Under the ramp to get to the upper level on the left side is a crawlspace (which we affectionately termed 'The Hole') in which you can hide in if too much shit spawns on your face. It also provides a spot where you can pick off some of the enemies and also damage the boss when he walks to your side of the room with little threat of getting your face stomped on. I recommend depending on your level that at least one member of your fireteam does not leave 'The Hole' as if the others go down outside it, it is difficult to revive them assuming you aren't a Defender Titan. Since it's arc burn bring an Arc sniper and fusion rifle as these will be really useful for DPS. The sniper tears into the giant tank boss thingy before the main boss. For the tank boss I recommend getting on top of the roof of the area where the guards like to hide in as the 2 dishes on the roof block the massive cannon really well, while not having any chance to get blown up due to it hitting a wall behind you. Bringing at least one source of void and solar damage is also recommended as the Operant Psion's and Imperial Centurion's shields can be difficult to take down, even when using the arc burn perk. Oh an be careful of the Psion's wave blast thingy as it has massive range and will OHK you.