What in the world do I do with this random vault monster?!

[Sasparillatango]

So I've just breezed through the Maze and the Sandworm Lair, doing all the starter zones to milk as much experience as possible since more experience means more levels, more levels means more talents and more talents means more versatility in combat situations -- I went to the first level of Dreadfall to see how I would fair and strode through that first level with ease. Then I see remember seeing a corner of a room off the corner of a hall in an area of the map I don't seem to have access to and I can't phase door anywhere near it, it is completely blocked off. So I take my trusty mattock and crush my way through stone and mortar and access the door, after an arcane eye just past that portal I see nothing and make my way in. This leads to a smaller hallway bordered by a few rooms and a doorway at the end leading to a small antechamber with some major shadow demon with only about health, shielding up and throwing on a displacement shield quickly and painlessly dispatches him leaving me with two more doors to contend with. On the side of one is another major demon, but nothing I don't believe I could handle, and on the other is a purple bordered monstrosity the likes of which I have never seen before. Thankfully my arcane eye gave me the information of his existence before opening the door and dooming myself, but inspecting the creature revealed something extremely off-putting to even attempting to fight this creature...

http://imgur.com/IkgHb

if I am reading that correctly... this boss has 500% resist in the all category

does this mean that he is completely indestructible? How would you even bother facing such a thing? Is there any hope whatsoever? Should I go for the shield up, run in looking for loot and porting out tactic or just leave him sealed away for all time? Note my level is 20, which is not too far off from the other creatures found on this floor but the level of this monster is only 33, and there are level 50 monsters behind the other doors.

[phantomglider]

If you've played Dwarves, this guy is like The Mouth. You can't hurt him directly, but he does open himself up to damage.

[Canderel]

He is a known character, and you can kill him, (as I'm sure you did by now?) just focus his friends...