Xvart shaman innate death magic immunity

[Zethrenx99]

So I recently discovered that the Xvart shaman have built in death magic immunity and my question is:
1) Is it based on lore and is suppose to be there
or
2) Can we have it removed as it adds unnecessary difficulty to a classification of spells that is already rarely used and doesn't have much worth out side of taking down the more frustrating to kill mobs?

And as an aside, could we take another look at mob saves? Ran into a troll with a will save that is 22 (10 more than my wizard at the time) and fort saves that where almost 30. Considering that the absolute max dc for spells is somewhere around 36ish give or take can we scale things back to reflect that? I feel that an archemage of a particular school of magic should have a decent chance of successfully casting their spell against anything.