Is he a solo instance by that I mean when you port to him and phase is that your personal phase or can others port in with you?
With the crystal when you port into a rare you see others arrive after doing the same thing, is it the same with this rare or is he just yours alone? If others can join it may be worth setting up kill groups otherwise if people are solo killing this mob its going to be a nightmare to kill as more people gain exalted etc...