
I dont get why shes doing all of this instead of just killing the queen and getting her revenge

Because she's not seeking revenge. The one who wanted revenge was the mother when she summoned the FL/MC, Belial, to possess her daughter, Ibleond (was that how you spell it?) Killing the queen and becoming emperor is just a contract, Belial has no personal stake in this. She's just gonna take the scenic route, while causing as much death and carnage as possible.
Bruh where is the story going