Eventually, after many losses and marginal victories, the main character is captured and brought before the "father," stripped of her weapons but not her armor or gear. Scene of her praying, asking for guidance and strength. He commends her, but expresses his intent to make her join them. She refuses, naturally, but he says that she doesn't have a choice. She is human, and weak. Quick flash of her hand gripping her armor. He grabs her face, moving his mouth closer to hers. Obvious overtones as something is seen inside. She hisses "you will not, for the Emperor is my strength" before jamming a melta bomb in its mouth. There's just a surprised look from it before boom.
All over the planet, the genestealers and cultists go all derpy, allowing the remaining sisters to easily mop them up. The last scene is them doing a slow march, burning bodies. The Canoness comes across the MC's rosary thing, offering her a blessing and commending her. The last actual shot is of the MC with her arms crossed, eyes closed, (nude, natch) smiling peacefully as she's bathed in golden light.