The "plan" was that she was enticed to shed the Imperium for not only self-preservation but also she is shown by the psyker, wether true or not, her fate if she remains part of the Imperium.
She sees her regiment deployed to defend against impossible odds whilst citizens are evacuated, the mission is folly as no evac ships arrive nor any reinforcements. She has to bear witness to her entire regiment being wiped out due to failings in the Imperium.
Her motives are two-fold;
1. Simple revenge against the Imperium that has failed her time and time again. The Imperium that demands the lives of herself and her comrades for nothing in return. They are bounced from one warzone to another with no time to consolidate their losses or recover. She wants revenge for being seen as nothing but ammunition for the Imperium to waste at will. But if it had to focus around any one person, it would be the Warmaster of the Achilus Crusade, the one who deems her expendable.
2. Plain, unadulterated, selfish hedonsim. A desire for all the things Slaanesh can offer that the Imperium denies.
Her premonitions are truthful and they benefit her greatly. Or she believes they have all been truthful but seeing as she has murdered someone because of what she believed they would do, there is no guarantee that all of the premonitions have been accurate.
Oh and I said carapace armour because that's what the Renegade starts with anyway.
I appeciate the help, all a bit confusing at present.
a humble traitor.