For the Chaos theory achievement we found a simple solution to do it. you will have a regular set-up of a group but you must have a mage in the group
Have the mage cast dampen magic on everyone. while you are fighting the boss have one of the dps kill the ADDS, not the orbs, and follow the group at the same time, the tank will kite the boss back to the area from where you first came from. you only have to move him untill he loses the debuff. make sure your healer is good on mana though.