Heart of Flame
After the attack on the Justice League's headquarters, in which most of her followers had either surrendered or been captured, Star Sapphire joined Lex's Legion in return for their protection. She swore allegiance to Tina Greer, Lex's head of the Legion and commander of the Vanguard (a faction of the Legion responsible for identifying and eliminating threats to Luthorcorp).

Star was disgusted at having to kneel before her former enemies, but she was desperate. Star was made to kneel before Tina Greer, someone who had terrorized her as a teenager. She stoically begged for her admittance into the Vanguard. She was completely humiliated. She despised Greg Arkin and Jodi Melville now more than ever, who had turned themselves over to the Justice League without a fight.

Star participated in the Vanguard's search and destroy operations in return for the Legion's protection and also for their help in freeing her former comrades, including Van McNulty (AKA Vendetta) and Jason Dante (AKA Hellfire). The Vanguard would attack anyone who presented a threat to Luthorcorp, including the Justice League.

Star found some solace in their battles with the Justice League. She had felt betrayed by them. Several of them had once been close friends of hers, and she felt that she had been villainized in her crusade to save humanity from dangerous meteor-freaks and aliens.

Over time Star proved to be a powerful asset to the Legion. Eventually she started to take pride in her abilities. She lost sight of her goals of the past. Most of the meteor-freaks came from the Lowell County area, and had been killed by that time. Only a few of them remained. Also, Star learned that aliens could be an asset to her. In her battles along side the Vanguard Star fought on many occasions with Sinestro, a Korugarian, and came to respect and even admire his skill with power rings.

Lex, however, came to regret his decision to bring Star into the Legion. Every time he looked at her he was reminded of the young, idealistic, smiling teenager who once gave him hope for the world. The path that was laid before her now was his fate, not hers. It was Lex's destiny since he was a child. He never intended for Lana to follow in his footsteps.