Taylor, Will (Children's literature author). School for Wicked Witches (Series) #2

Perfect for fans of WICKED, WITCHLINGS, and THE WIZARD OF OZ, this magical series returns with magical adventures, friendship feuds, and a whole lot more. After successfully escaping back to the School for Wicked Witches, 11-year-old Ava Heartstraw and her friends Crow and Henry discover they're more behind in their magical education than ever--not to mention in serious trouble. When the arrival of an unexpected visitor spells disaster for the school, Ava realizes she may be able to save the day and redeem her shaky reputation... but only if she pairs up with Tinabella, her best-friend-turned-enemy, on an epic hunt to unravel a thousand-year-old mystery. What's a young witch to do?