This taint can manifest in various ways, from the subtle corruption of an individual's psyche to the wholesale adoption of alien technology and culture. The Mark of the Xenos is a reminder that, in the grim darkness of the far future, even the smallest hint of alien influence can have far-reaching consequences.
Deeper in the underhive, Arcturus discovered a hidden chamber filled with ancient relics. At the room's center lay the artifact: a crystalline orb etched with strange, Eldar glyphs. As he reached out to claim it, the orb flared to life, imbuing him with a vision of the distant past. Warhammer 40K - Mark Of The Xenos.pdf