Can't speak for other group makeups but the secret for 5xshammy for normal mode on this guy are the earth elementals.

Drop them out front, hang back a bit, and nuke like crazy. When the orbs spawn the elementals get hit and debuffed, you may or may not need to start a big heal just before 20% , then finish him off. Look at Veronika's movie for Heroic Mgt in the movie forum, similiar idea - it works flawlessly in normal mode but for heroic I can't seem to get it to work like she does. For some reason I take massive damage, while in her video she has 1 person that takes a lot of damage and dies... don't understand how she managed that.