(Not actually sure if this goes here or Priest subforum)
So apparently a bunch of priests were bored and raided the entire Normal Nighthold, all 10 bosses. Also did Heroic EN at some point before that I think.
Like that:
The videos are here. Index_1 for promotion video, 2 for Skorpyron, etc. I think.
By the looks of it they generally have 6~8 healers in a raid team of 21~24, both Disc. and Holy. No idea how hard it is to actually raid Normal without a tank, but hey, if people bothered I don't see why other people can't take a look unless the music is terrible.