Phase 1: Tank and Spank
Phase 2: Spam Icy Touch, Death Coil, Blood Boil and Death and Decay. If you want to get your Plague Strike's disease (forget the name) just wait for an add to appear, hit them with Plague Strike then Pestilence/BB (if talented for Roiling Blood) while under Ony. Takes about 3 minutes.
Phase 3: Tank and Spank - Fear edition.