To the below post, I never tried that but might work. its nice to have a good puller. this guy spawns inside the building north of the open middle area where lots of mobs roam.
What we did is camp in doorway/hallway near where Excrud spawns and pull pher out form there. His pher seems to be just the statue standing in middle of room but i assume it might be others as well. we had puller clear small path to the building his pher is and pulled phers from there. its a long pull but not many safe spots. If the below post works then i guess u can camp inside room if u can make it there. otherwise DO NOT FIGHT any mobs that are INSIDE that room , inside that building, they are all buffed with a massive DS. To Dispell DS (only way i can 100% confirm) is to pull those mobs OUTSIDE that building and the buff with go away instantly.
Having a druid cast Silver Frost will debuff the Champion buff on all the mobs in the area .... eliminates the Damage Shield .... yay he went down super easy after