White Dwarf #286

he baroque and priceless force staff carried by Eldrad Ulthran is far more than just a symbol of his office, and is even more ancient than the venerable Ulthran himself. Made from the purest wraithbone, it bears the spirit stones of the first Seer Council of Ulthwé.
Each Craftworld has an infinity circuit: A complex wraithbone endoskeleton that runs throughout the Craftworld and houses the spirits of dead Eldar. The Staff of Ulthamar forms a hyperspatial link to the infinity circuit of Craftworld Ulthwé. To the weak, the babble of thousands of ghost-voices channelled by the staff would quickly erode all sanity. To one as strong as Eldrad, the staff can act as a conduit, directing a reservoir of psychic power to aid his fellows or destroy his enemies.