OK, here's a couple boss vids in Underbog of my 4 priests with a pally buddy tanking.

http://files.filefront.com/Ghazan2av.../fileinfo.html
http://files.filefront.com/Hungarfen.../fileinfo.html

Note that I could spam more flay/mind blast/etc. but I'd rip aggro right off him and that would be counterproductive.