This level will start off with a few flying cultists that you have to kill. There is plenty of room to move around so these should not cause too much of a problem.
You will then enter a room with two enemies, one standing on a pedestal and another hanging from an apparatus above. There will be four spiked wheels on the wall that have four bodies impaled on them. The blood from these bodies will form a shield around the lady on the pedestal that protects her from any damage.
When you get into the room, a gladiator will spawn, but don't bother trying to kill him since he will just respawn if you do. As long as you keep your distance, your comrads should keep him busy. Instead focus on shooting the bodies stuck to the four wheels (I used the scope on Black's rifle to zoom in and get an accurate shot). Once you shoot all four of them off the wheels, the guy hanging on the top apparatus will swing out and turn his back while he rotates the wheels to reveal four fresh new bodies. His back is his weak spot so let loose on him when he turns around (I used Black's ghost bullet at this point to get a good shot at the middle of his back). He will swing back to his originaly position and then you have to repeat the process of shooting the four bodies off the spiked wheels.
Once you kill the guy hanging from the top, three cultists will continue to spawn instead of the gladiator. These cultists can be a pest and will make quick work of your comrads if they are not taken care of. You will have to knock the four bodies off the wheels one more time as fast as possible while dealing with the cultists (this is probably the point at which you have the most chance of being incapacitated). I stood as far back in the room as possible and used Black's ghost bullet as the cultists were charging trying to pop at least two of their heads, then steering the ghost bullet up to the bodies on the wheels.
Once you clear the bodies for the last time, the shield protecting the lady on the pedestal will be down. Let loose on her with all you got, Black's grenade launcher works well for this. The cultists will continue to spawn, but should not take too many hits to kill her. Once you kill her, the level is done.
Just a general tip: If you notice that Rawlings goes down, make an extra effort to try to heal him. He possesses the healing magic and does a decent job of reviving your other comrads if they go down, so you'll want to try your best to keep him alive.