The Angrenost is a heavily-defended assembly hall located deep within the Layil Empire's AiBorg Factory at Losei. Its function is to manufacture AiBots and other Imperial weaponry, including tanks. The hall appears to be operated by AiBots themselves, who are situated in glass-panelled control rooms overlooking the hall.
Durak's raid on the factory culminates in her attacking the Angrenost and destroying its control centers. However, one of the explosive charges laid by her earlier goes off prematurely and begins to destroy the factory. With no way to escape, Durak stoically accepts her death and perishes in the ensuing explosion.
Angrenost is a word in the fictional Sindarin language created by J.R.R. Tolkien. The word translates into English as 'iron fortress', and is also the basis for the name of the fortress of Isengard in The Lord of the Rings. Isengard's verdant fields and grounds are destroyed by its occupant, Saruman the White, and replaced with machinery for creating weapons - just as in Sine Mora, the once-lush valley of Cardinal Canyon is transformed into the hellish landscape surrounding the Losei AiBorg Factory.