Use a full PDT set full time so you can pull more mobs, don't 2 hour so they don't all die at the same time, and use whatever atmas you would normally use so you don't have to switch later.

Real Advise:
Mobs only walk in a clockwise rotation around you when they group up, if you force them into a wall they cannot do this. What you need to do is pull everything into a wall on your left as you return to where your mage is waiting for you, and turn to face them, making the wall on your right, and you need to be directly against this wall, lock on whatever you're engaged to and walk backwards a little and this will pull everything directly in front of you because when the mobs can't walk in a clockwise rotation around you, they will just sit on top of each other.