Well, with all these comments on how it's glitched, mine went fine, albeit a tad long because I wasn't in a group.
I got backhanded away, just like others. A warning said to rush back and kill him. I got there, Kurdran Wildhammer was tanking him, with Matias Shaw and two others fighting (one would heal me for 35k every now and then). I commenced dpsing him as a hunter. Once he got to like 90% health, more messages appeared. They said to activate the altars to receive buffs, while avoiding the dark circle of death which tics for 10k damage.
These are the buffs
Air - Melee, ranged, spell casting speed increased 50%
Fire - Increases damage dealt by 50%
Frost - +50% crit
Earth - Damage taken reduced 50%
Sometimes, I do not know what causes this, I would get a running speed buff.
Every now and then, a warning would say to revive my teammate. It was always Kurdran, and I just right clicked him, and a second later he was tanking again.
The boss would sometimes do an Earthquake move where he would pound the ground, which would cause knockback on my cobra shot and about 3k damage every second.
When he got to like 10%, he grew bigger, with a force field around him. All my attacks only hit for 10-20 damage. Some guy talking said to use his horn, so I did (it was marked with a gree arrow on the ground where Kurdran was usually). Boss shrunk back down, and lost his force field. Reinforcements apparently arrived, but I didn't notice. He lost that last 10% pretty fast.
Went back to Victors Point to turn in.