Currently running a Dwarf Bulwark that is now in the Sanctum, have closed the 4 portals and even killed one of the 2 bad guys, i'm now facing some very odd thing.
The remaining bad guy has some silly 72% resist all (+ some other high resistance) , has obviously more than 10000 health (so basically horrible combo high health + resistance to everything making it overpowered )
And regenerate very regularly.
That is all in itself making for a ridiculous battle in which all i can deal is low damage, then run away to avoid dying, and once i get back in battle, the guy is near full health again.
But at least that ridiculously overpowered guy, i understand why it happens, the numbers makes it clear and it's obvious it's stopping nearly all my multi-elemental and physical damage.
But what i don't understand is the following : the guy hit -very- hard each turns.
Nearly each turns i get near between 200 and 250 lighting damage, and between 250 and 300 cold damage according to what i see when i press H ingame.
So even my Bulwark and his very high health (more than 1300) can't fight for long without escaping.
So i gave a look at my character resistances, that are all high considering i have found some exceptional bunch of items since the Orcs Pride.

It would be arcane damage i could understand as i don't have been lucky enough to find worthy piece of items with arcane resistances
But in the present situation how it is possible that he deals -that- much lighting and cold damage to my character near to each turns ?
If i trust those numbers my character should be basically immune to both those types of damage ?
edit : by luck i still had a longsword with crippling effect on hit, despite it had less damage, the crippling effect helped to keep the incoming damage lower, allowing me to be able to regen and heal before dropping too low in health.
Thanks to this sword i finally beat him and won the game.
But still i don't understand how the resistance works