I recently found a way for rogues to easily kill the priests shadowfiend. Very useful for arena.
All you have to do is use blade flurry and have the shadowfiend be the one recieving the damage from it. Usually when you attack a shadowfiend 90% of the attacks will miss / dodge / or be parried. Blade flurry however, can not miss.
for example: a priest uses his shadowfiend on you. Use blade flurry and start attacking the priest. All damage done to the priest will also be done to the shadowfiend.
couldnt find this through search, sorry if it has been posted.
EDIT: also seems to work with Sweeping Strikes for warriors