Well I think solar brilliance is mostly just anoyance as yer undead armies will mostly have 10+ mr after blessing thus casualties will be acceptable from it. Ye must think as russian in ww2 general regarding yer undead thousands... thousands there thousands here we got thousands to spare they don't
I would be much more scared if enemy spammed those fire/ice mass army kill spells. In my last game I seemed to lose tons of troops with ma ermor to that frost version... armies were mostly undead.
What la ermor must be most afraid is multiple front wars... they will kill him no matter what but those who fight ermor will fall with it.