Max hit on 3900ac pally (max shielding) was 2391. Few rounds were 2k+, most rounds were 455-1200s. Had self, shammy and cleric all spotting, and her DPS was still pretty heavy at times. I'd recommend a defensive warrior tank if you can afford one, or a 3500+ac knight :)
This mob casts, amongst other things, Deathly lifetap, it also procced a FD on me during the fight. Also it cast a spell called "grip of Physical terror".