Isstvan Extremis

Isstvan Extremis is the outer augury-nexus of the Isstvan system, silenced by Emperor's Children and Death Guard so Horus could blind the inner worlds before the virus-bombing of Isstvan III. Warsinger outposts and early-warning gear died there in the opening skirmish of the Atrocity. Lexicanum has no standalone Extremis article; the system page carries the one-line status, and the Isstvan III battle article names the assault.