Gorak the Ancient, comminly referred to as the "lightning boss", is a ward check for your group due to his massive lightning AOE damage in his second phase.
Before the fight clear all non-sprite mobs and leave a few sprites to feed morale while you prepare/explain the fight to your group. This is mostly for tanks who will need Distracting Bellow to help lessen the AOE damage during phase two.
Phase one: is a general tank and spank until an AOE knockback is triggered and phase two begins.
Phase two: Tank should use Distracting Bellow if possible. Gorak the Ancient stands in place and shoots lightning to a random person every five seconds which does increased damage when other party members are close to the reciepent of the attack. Everyone should spread out a little expect one dps on Gorak. Tank should guard the dps on goark and be ready to taunt Gorak when he is no longer immobile and phase one begins.