Also each doppelganger only has two abilities relating to each class, although mages are unable to get the fire strike ability.
Squire - Hateful Strike / Shield Slam
Ranger - Ensnare / Remedy
Thief - Embrittling Acid / Coup de Grace
Mage - Fire Strike / Frost Cage
Bishop - Heal / Crippling Curse
What S0ulseeker said, pulling the first doppelgänger with a druid works best
Just get the druid to initiate the battle, they usually get agro for the first doppelgänger.
Make sure the wolf has agro, then move on to attacking/healing with your team.
The boss itself is easy to manage once you get the idea.