The Eldar Dead March To War, Lead By Their Necromancers - Warhammer 40k Lore

There are not a lot of Eldar left... And in some craftworlds like Iyanden the dead outnumber the living many times over, fortunately for the Eldar, or unfortunately for their sense of ethics and morality. The dead can be roused to fight once more! Possessing wraithbone constructs the Wraithguard march to fight the enemies of the Eldar once more, lead to battle by their Spiritseers.