I just don't see this being possible for a long time. You'll need Dark Bargain to survive the transition phases, absolutely 100%. That rules out Destruction immediately (my Pet gets absolutely destroyed without Soul Link, even on normal, as Destruction.)
Affliction you'll need to spam Drain Soul in order to keep your pet alive, and I just don't see it being able to put out the DPS to get into phase 4 with a manageable amount of meteors. I also don't think Phase 4 will be particularly easy, given that the whole room will be covered in Dreadflame and you won't be able to heal yourself enough whilst also drain souling to keep your pet alive.