Having trouble with the Eye of Zhaitan?

The Eye of Zhaitan in the quest A Light in the Darkness is one of the harder story line bosses you will encounter.  His beams do a lot of damage in a short time.  The most effective strategy is to use ranged weapons and to keep chipping away at him from around one of the large statues in the area, dropping back behind cover whenever he channels his beam attack.  If done properly, he'll likely spend a lot of time attacking your partner, which is a good opportunity for you to unload on him.