Kickass AI tactics or just a few billion hp? If it's the later, I'll pass on it.
I think it's a slasher of veils (Ricardo said something along the lines of it being the slashers ugly brother) with more health, maybe other bonuses, abilities. Not sure. Never fought one. Basically it hits very hard, area lethal poison, pulls attackers, kills pets in about 5 seconds, makes fire around itself, has the big white screen attack (whatever that is) seems to heal quickly. Even when those red guys had it trapped with bag balls so it couldn't move no one was able to really attack it for more than a few seconds, doing little to no damage.
I think it would take a real effort to kill it, especially since it seems to have a bonus against pets, and pretty much everyone seems to use a pet. Group healing the heartiest pet anyone has? Maybe cross healing warriors, plus mages healing them? I dunno, it's a scary monster, that's for sure. Me and my wolf were pretty much 100% useless.
I'm quite sure it has a item to drop, but if the EM being there for the event wasn't enough to get people together to fight it, I don't know what will be enough encouragement.