Realm of Chaos - The Impossible Fortress: Tzeentch's sanctum sanctorum, the Impossible Fortress, is said to lie at the centre of the crystalline maze, the Crystal Labyrinth, if indeed geographical descriptors such as "centre" apply with any accuracy to this inconstant realm. Some consider this as more akin to a central belief or conceit that might drive a series of thoughts than an actual location, as nothing of this area has physicality as mortals would comprehend it.While this ætheric edifice is in constant flux, many have described it as a crystalline castle composed of the same sort of material as the labyrinth that surrounds it. Imbalanced spires spontaneously emerge from the ever-shifting foundation of the Impossible Fortress, as do towers of blue and pink flame and searing Warpfire.Gates, doors, and portals slowly open, as if yawning with the ennui of ages, only to slam shut like mouths of terrible beasts and then disappear. Mortals shackled by the psychological manacles forged by a lifetime of habit and enculturation in the material realm cannot fathom the perverse design of Tzeentch's home.Indeed, as the name of this fastness implies, even the most visionary and heretical designers of the material realm could not draft plans for the maddening architecture of the Impossible Fortress. Few Daemons, save the most powerful Lords of Change, can navigate its corridors, but as these creations are intelligent distillations of the madness that makes up Tzeentch's realm, they thrive all the same.Deep inside the Impossible Fortress, according to some profane accounts, lies Tzeentch's fabled Hidden Library. This infinite collection of tomes, scrolls, and parchments of every kind contains every scrap of knowledge and thought ever recorded in Creation; stories written and unwritten; histories true and alternate; and accounts of futures potential, actual, and imagined.Many of the volumes are so weighty with knowledge that they gain a sentience of a kind and spend centuries chattering to passersby, arguing with one another, rewriting themselves, and then reorganising their placement accordingly. Magical chains of Warpflame help to protect the books and bind them in place.Horrors serve as grotesque librarians and work tirelessly to re-shelve the works, catalogue the collection, and maintain what passes for order in the Impossible Fortress, though as the concept itself is anathema to the Great Mutator, no mortal could possibly fathom such a design.As with so many things associated with the Changer of Ways, few things are always as they seem. Although the Crystal Labyrinth, the Impossible Fortress, and the Hidden Library often appear (or at least are often perceived) as delineated above, by no means are these descriptions consistent with every narrative provided by those unfortunate mortal souls who have visited Tzeentch's domain.Bock Sammaelle, dubbed the "Lunatic Scrivener of Hamclov Prime" by the hive city princes who acted as his patrons, claimed to have travelled to and returned from Tzeentch's realm in the early 41st Millennium. Sammaelle attested that he saw nothing but a bleak hill on which a single, leafless tree stood.Daylasse Dial, the Heretic illuminator of Phalan 10 who was later executed for heresy, described Tzeentch's realm as a barren, desert landscape populated by deformed, headless humanoids that continually split and reformed into new bodies.