Isstvan Sector

The Isstvan Sector is the administrative cube above the Isstvan System, the paperwork around the eight-planet well where the Horus Heresy stopped being a rumour.

Isstvan III was virus-bombed; Isstvan V was the drop site where Ferrus Manus died. This row is the sector box, not a second massacre page. This map parents the system here even when some lore files the well in Ultima.

The Isstvan Sector still matters because every later civil war points back to this cube. Unofficial maps keep the Obscurus parent and leave III and V as children of isstvan-system.