Titan.

[Goom]

From what I can tell, you are doing nothing wrong. I will say that this fight gets much easier at lv35 when you Regen. With Regen, you can just keep that up on all the party members during Phase 4, making his multi-stomp much easier to heal. Phase 1 is all about dodging. If you are having trouble getting out of the bad zone quickly enough, I'd recommend constantly strafing around the boss, only stopping to heal. If you are already moving when the bad zone spawns on you, due to latency and reaction time, you are far more likely to safely make it out of the zone. As for the entomb in Phase 4, make sure your DPS are on top of it. Side note: Try and stay away from the tombs, I've gotten a knockback zone spawn on me and I tried to side strafe, getting stuck on the tomb