Being the strategist of the Macrae family reigning at the top of Elizabeth family she had already anticipated Kolt's move if he were to be at his wit's end.
As a result she had come up with various ways to help Zach without compromising her identity.
Sarah was a senior water mage with years of experience and inherent talent of the Macrae family in wielding and manipulating water element mana. The fog had in fact been the concoction of several mages belonging to the Macrae family with Sarah leading the orchestra of mages to play a deceitful and illusory tone that pestered and hindered the royal forces.
As she controlled the fog to stay in place despite the attempts of the wind mages, she ordered her men to change into white clothes that were free from all kinds of markings and blemishes. As a result it was hard to deduce the forces these people belonged to. Sarah had even brought along face masks in order to keep anyone from recognizing them later on.