At the centre of the Crystal Labyrinth, hidden from those who have not the insane insight to find it, stands the Impossible Fortress. The architecture of the bastion is constantly replaced by new and ever more maddening spires, gates and walls. doors and other entrance points yawn open like starving mouths, before clamping for eternity moments later, barring all access. Within the Fortress time and space does not exist at all and gravity shifts and changes, or disappears all together. Lights of every colour, some even unknown in the real universe, springs from the shifting walls. For mortals, who are so locked in their physical ways, the fortress is impenetrable. Men are driven insane, while their bodies might implode or be pulled apart by the forces unleashed by Tzeentch's passing thoughts. Even immortal daemons cannot easily endure the twisted horror of the Impossible Fortress and only the Lords of Change can safely navigate its corridors, and tread the secret paths that lead to the inner sanctum of the fortress, the Hidden Library, where Tzeentch, the puppet master himself resides, eternally plotting.