Warlock and hunter were definitely among the first.
Anyway, I also do it similar to williee, but:
Sanguinar dies in void reaver's hallway, capernian at solarian's door, and the other 2 at the back of solarians room. Forces them to come one by one in p3, and makes the adviser phase stupidly easy.
As for p4, I'd really benefit from more practice here
, I suck at it. I just berserk early, push his health down as much as I can, and run. Run like the wind. It's pretty easy to heal through pyroblast, especially with the cosmic infuser buff, and by the time I have to turn around berserk is nearly ready. I actually managed to "kill" him this week before he entered the final phase, so that all I had to do was 1 melee swing after his RP. No mount