Sigma-Ulstari

Sigma-Ulstari is an Imperial forge world and the only warden planet inside the Cordon Impenetra, which borders the Ork empire of Octarius. It lies in the Sigma-Ulstari System, in the Octarius Sector of Segmentum Ultima. No coordinates are recorded.

About three-quarters of its surface is covered by deep oceans of toxic waste, so its forges stand as tower-factorums. Since the Octarius War began, the world has suffered at least three invasions by Orks and Tyranids and has remained in Imperial hands.

In the later stages of that war, dated only to M42, a final Ork and Tyranid attack nearly took the world despite the defences of Fabricator-General Einrekh Phlagustok. An Indomitus Crusade task force under High Marshal Helbrecht saved it. During the battle he killed the Ork warboss Tuskagrob Wurldkilla. The world was afterwards stable, but it was still in danger.