Part of the reason immunities are so good.
Undead Immunities - whole slew!
* There is somewhere an item that can only be used by elves that gives undead immunities.
* 8th level spell: Viel of Undeath (or some such)
* Necropolitan (only costs ~3K exp)!
Similarly freedom of movement, mind blank, death ward, ilmatar's blessing (?), Foresight, etc. While this shouldn't be the focus of the guide, it probably does deserve a section.
There are also a ton of spells (Ruin Delver's fortune, one of the ones in the Destiny Domain, Wings of Cover, etc.)
Best,
David