A smog-choked hive world of the Drusus Marches, Thical is infamous for endemic corruption, crime syndicates, and political decay. Billions toil in overcrowded tiers, while Hive Lords, Administratum clerks, Arbites, priests, gangs, and Mechanicus detachments jostle for influence.
Cult activity, mutant warrens, and xenos-smuggling plague the underhives. Despite its instability, Thical remains a vital contributor of manpower, munitions, and wealth to the Calixis Sector—its corruption tolerated so long as its tithes flow.
Ignis Aeternus WH 40K campaign notes 