In Mulan (2020), Xian Lang's character is a sorcerer of some sort addressed as Witch throughout the movie. Right from the beginning she is shown to have capabilities to impersonate others/possess their bodies to infiltrate.
In two instances she has successfully infiltrated the palace and is in close proximity of the Emperor.
But even then she does not try to capture or kill him. Why is that so?
As answered by Yu Zhang, Boris Khan wants personal revenge which is why the Witch does not kill The Emperor.
But my point is, it's due to the Witch's help that Boris Khan is able to reach the Emperor and take him as his prisoner. That could have been done easily by the Witch. Why go to war? Kind of a long way to get to the Emperor. That seems like a plot hole to me, hence the question.