An Eldar Spirit Stone, also known as a Waystone and a Dreamstone, is a small, seemingly precious gem carried in a variety of different aesthetically-pleasing settings on an Eldar's chest, used to save their souls from destruction by Slaanesh. At the moment of the Eldar's death the stone acts like a "psychic trap" absorbing his psychic self and preventing it from entering the Warp and being consumed by the great nemesis of the Eldar race, the Chaos God of Pleasure, Slaanesh. The Waystone can then be brought back to the Eldar's own Craftworld and embedded into its Wraithbone core, where it will grow into a larger Spirit Stone. Once the stone is implanted, the individual Eldar's soul it contains can travel freely through the Wraithbone, mingling with other Eldar souls and forming part of the communal spirit of the Craftworld itself. All the souls within a Craftworld collectively exist within the Infinity Circuit. In times of dire need, the Eldar are also able to retrieve the Spirit Stones of long-dead Eldar heroes and place them into the artificial bodies of Wraithguard and Wraithlord constructs. These Wraithbone constructs are then piloted by the Eldar soul, which experiences reality in this form as a dream. This process is considered little better than necromancy in Eldar culture and is only done as a last resort. Spirit Stones can also be placed within certain Eldar vehicles like gravity tanks and Eldar Titans where the stone allows the captive Eldar's spirit to control the vehicle in case its living pilots are incapacitated, similar to the way the artificially intelligent Machine Spirits found in certain Imperial vehicles like Land Raiders can take over control of the vehicle even when it is unmanned. The Eldar Warlocks who specialise in this process are known as Spiritseers. Iyanden is an Eldar Craftworld with a very small population following an assault by the Tyranid Hive Fleet Kraken and is known for its greater use of these Eldar "living dead" than other Craftworlds.
There is one primary source of Spirit Stones: the old Eldar homeworlds that lie within the boundaries of the Eye of Terror and are now known as the Crone Worlds. Acquiring new Spirit Stones is extremely dangerous because the Crone Worlds exist within the Eye of Terror. In Eldar mythology the Spirit Stones were created by the Eldar God Vaul from the Tears of Isha. This tale is taken as a metaphor by the Eldar for the crystallisation of the psychic energies of the Eye of Terror into the Spirit Stones.
It is commonly believed that when enough Eldar souls have been gathered within the Infinity Circuits of the Craftworlds, a new God will emerge within the Warp, the first Eldar God to be created since the Fall of the Eldar; Ynnead, the Eldar God of the Dead. It is hoped by many of the Farseers that this new God will be powerful enough to vanquish Slaanesh, freeing the Eldar from their doom at the Prince of Pleasure's grasping hands.
The graphic novel Daemonifuge features the Spirit Stones only passingly, but names them Soul Stones instead. However, the Eldar codexes name them as Spirit Stones. It is not known exactly what happens when a Spirit Stone is destroyed, but one can guess that the soul within is lost to Slaanesh. Also of note is that in the novel Dawn of War, a Spirit Stone is smashed by a Power Axe, resulting in an incredibly loud metallic ringing, and then an explosion that not only destroyed the Power Axe, but also sent Trythos, the Space Marine wielding it, flying a few metres away, thus indicating that Spirit Stones are a potent source of psychic energy.
- Codex: Eldar (4th Edition)
- Codex: Craftworld Eldar (3rd Edition)
- Codex: Eldar (2nd Edition)
- Farseer (Novel) by William King
- Warhammer 40,000: Wargear (4th Edition)
- Warhammer 40,000: Compilation (1st Edition)