Astra was a founding member of the Imperial Guard and first clashed with the X-Men over the fate of the Shi'ar Empress Lilandra. Later, when Deathbird was Empress, she commanded the entire Imperial Guard to fight the combined forces of the Starjammers and Excalibur so that she could claim the power of the Phoenix Force for herself. During the battle, Astra surprised Shadowcat with the ability to hit her in intangible state, since she could match her molecular density.
During the crisis that came to be known as Operation: Galactic Storm, Astra was amongst a small contingent of the Imperial Guard that defended Lilandra against the Kree super-team known as Starforce. Astra was also with the Imperial Guard when they defended their Empress Lilandra against an assassination attempt from the Inhumans, who were under the control of Ronan the Accuser at the time.