Calixis Sector - Scintilla: Scintilla is the capital world of the Calixis Sector of the Segmentum Obscurus, and is a thriving Imperial hub that supports the largest planetary population in the sector. It is dominated (some observers say "shared") by two vast hive cities, Hive Sibellus and Hive Tarsus, into which the vast majority of the planet's groaning population are crammed. Despite the dominance of the two great hives, the "offspring" communities of Ambulon and Gunmetal City contribute significantly to the planet's economic function.Scintilla is a world of splendours where the wealthy and powerful compete with ruthless appetite. Astonishing magnificence abounds, from the wondrous fashions of the hive nobility to the towering spectacle of the hive cities themselves. Landmarks like the Lucid Palace and the Cathedral of Illumination are famous throughout the sector.Scintilla is also a world of corruption. Moral decay eats away at the noble houses, members of which are often deluded by their own wealth and status. In the rarefied culture of the high-born, the corruption of power and privilege runs deep. Noble houses consider themselves (sometimes correctly) as above or outside of Imperial law and can wield immense influence. Their attitude towards those lower-born is callous: it is not unknown for thrill-seeking degenerates from noble houses to prey upon lesser Humans as sport, often feeding secret Chaos Cults devoted to Slaanesh.At the other end of the social spectrum, the underhives are rife with mutants, outlaws and ultra-violent gangs, as well as the psychotic zealots of the Redemption. The middle hivers trapped between the aristo spires and the rancid underhives live out thankless lives of unending toil, where ignorance is a virtue, and death is a reward for a lifetime of loyal, drone servitude, fulfilling the exorbitant tithes levied on Scintilla by the Adeptus Administratum. It has been this way since the days of Golgenna Angevin, and Scintilla's various corruptions are so deeply ingrained that they have become invisible even to those who perpetrate them.Scintilla's most important features are its two hive cities: immense, multi-levelled arcologies that house billions of Imperial citizens. Both hives on Scintilla are largely independent, ruled by councils drawn from the nobles of the spire. The majority of the inhabitants are middle hivers, the labouring classes, without whom the planet's manufactoria and trade houses would cease to function.Almost all middle hivers are owned by, indentured to, or employed by nobles from the powerful, sector-wide Great Houses or from Scintilla's own lesser houses. The poorest and most neglected areas are the underhives: polluted, crime-ridden places where life is cheap and brutal gangs struggle for supremacy before violent death inevitably claims them. As long as the violence does not spill over into the middle hives, the authorities are happy to let the gangs murder each other in the cesspits of the underhive.Scintilla's two great hive cities have always competed with one another for prestige and influence, but no rational observer could fail to acknowledge Hive Sibellus' political and economic dominance. Geographically the larger of the two hives, it is often referred to as "the Capital" or the "ruling hive," and is both the seat of political and administrative power on the world, and the centre of the planet's manufacturing might.Hive Tarsus functions as a dark, shadowy twin, popularly referred to, by Sibellians, as the "Other Place." Hive Tarsus is a mercantile hive city and controls all off-world trade and commerce. Neither hive city could function without the other, a fact celebrated in Scintillan proverbs and myths. However, neither great hive city would openly admit to the importance of the "offspring" communities, Ambulon and Gunmetal City, both of which wield considerable influences of their own.