Ulgu, the Realm of Shadow, is the twilit plane governed by the grey wind of illusion, deception, and mystery. It is a realm where nothing is as it seems: banks of enchanted fog roll across shifting landscapes, mirror-mazes stretch to the horizon, and paths rearrange themselves behind travellers so that no map ever stays true. Distance and direction are treacherous, and the realm delights in leading the confident astray.
Ulgu is the eternal counterpart to Hysh, the Realm of Light, the two forming a bound pair of shadow and illumination at the heart of the realms' cosmic symmetry. Where Hysh exposes, Ulgu hides, and its grey magic teaches that concealment and misdirection can be mightier than any blade. Assassins, spies, and shadow-mages prize its lore, and the murder-cults of the Daughters of Khaine make their bloody home among its murk.
The realm's deceptive nature makes it nearly impossible to conquer, for an invading army can march for months and never find its foe, or find itself surrounded without warning. Even the Dark Gods struggled to hold it during the Age of Chaos. To those who learn its rules, Ulgu offers unmatched sanctuary and secrecy; to those who do not, it offers only the slow, patient erosion of certainty, until the traveller no longer trusts their own eyes.