Overview
The Octarius Sector is a war zone defined by xenos violence at a scale that threatens to spill beyond its borders.
Imperial interest often centers on containment, because victory can feel less immediate than preventing the fire from spreading.
In Nihilus conditions, containment becomes harder to coordinate and more dangerous to neglect.
M41 and M42 status
Violent xenos war zone on the eastern map.
Nihilus-dimmed war zone with escalating fallout.
Timeline
Eastern watch stations record large-scale xenos escalation.
Containment strategies are revised as the war grows less predictable.
Kryptman's Gambit lures a tendril of Hive Fleet Leviathan into the Ork empire of Octarius, igniting an all-consuming Ork-Tyranid war (sources date the invasion 989-999.M41); Ghazghkull later arrives to lead the greenskins.
Rift disruption weakens regular oversight of the sector, and the Cordon Impenetra fails to seal the war zone.
Nihilus hazard charts mark Octarius as an expanding strategic concern.
Cartographic positions and several administrative details are intentionally approximate where published Warhammer sources conflict or provide no canonical coordinate system.