For those of you not familiar with this boss fight, here's a quick overview. Big floating-eye poison-dropping tentacle-waving boss guy can't be touched until you take out four waves of Fel Orcs first. With a mix of elites and non-elites in each wave, these orcs were hard, but not crazy hard. After the last one dies, you can face off against Broggok who isn't as difficult as the orcs before him.
The problem with this event is that your group's casters were usually out of mana at the end of the Fel Orc part of the event. Though Broggok isn't crazy tough, he isn't a pushover with zero healing mana available for the fight either. A typical strategy was using some form of crowd control on the last orc in the last wave to allow you group to regen mana before triggering the boss.
But with the last patch, the game has a new twist.