This lil guys can't be charmed. Didn't see it posted anywhere so I figured I would let people know. Made for a long and boring chant kite killing like 8 of em :).
3200 damage nuke ate about 25% hp on one of these guys. So doing math they have about 13k hp give or take a little. Also, when I tried nuking one down (fire nuke) it was resisted once, partially resisted once, and the other two times it landed..so they aren't too terribly resistant, but they aren't really weak either. I had much better luck landing my dots.
Also, they have spawn time of about 30mins give or take a minute. Hope this helps. =)
As a note, these fellas can hit up to 355, and they do double. They can mostly be single pulled except for the pair by the front entrance of the castle. The north end of the wall is free of mobs, so does work as a pull spot, or you can fight them at their spawn location. They run at Low health, and tend to walk the parapet's, so it's easy to knock them off in the water and have problems killing the, or getting trains from the yard on you. Pulling can be a little tricky because of this as well, you don't want to get too far ahead of them around the curve of the wall, or they'll drop over the side. Sometimes they jump back up, but sometimes they take the scenic tour to you and bring friends along to play. They may hit hard, but they don't really have many HP's compared to the planes nowadays.
With my 63 Druid I was clearing the castle wall and they drop diamonds, lots of other gems, lots of words and runes not listed above but they all sell for very good plat in the bazaar. I have spent dozens of hours here and so far I believe only 2 had nothing on them.