So I had an idea after healing heroic Halfus that stacking atonement spec Disc Priests can pretty much bring down anything. (Well, almost anything...) Got some buddies together, and we smited 10m Marrowgar to death this afternoon. We used no other healing except PW: Barrier and the occasional PW:S for Rapture procs. Stay tuned for more all-Disc kills. Hoping to put together a group for 25m Arthas in the very near future!