#1 - use search, its been answered every day for the last 6 months.
#2 - all you need is retribution and healing breeze, leave all other skills empty or fill with useless skills for the doppleganger to use - sacrificing, life attune, etc.
Check this topic, as well as others in the PvE forum. The question has been previously anwered, and there's a few topics already floating around as to beating your doppleganger.
