Baba Yaga: The Witch's Apprentice - Book 2. Baba Yaga, #2

In a matter of days, the village was consumed by whispers: Sajo was to blame for the return of Yaga's sisters to the dark heart of the Kelebija Forest. Shunned and restless, unable to find peace even in his own home, the wounded boy seeks refuge with the one person no one dares to trust - Yaga herself. To everyone's shock, the witch takes him in as her apprentice. For Sajo, it is a dream come true.
For the witches, it is an outrage. Roga and Jadwiga are appalled. Witchcraft, ancient recipes, forbidden spells - such knowledge has always belonged exclusively to them. Allowing a mere boy access to their secrets is reckless, dangerous. unforgivable. Determined to drive him away, they make his training a living torment. But Yaga has her own reasons. Defiant and amused by the scandal she causes, she proudly brings Sajo to the annual witches' sabbat on Midsummer Night - a decision that sends shockwaves through their world.
For the first time in years, Yaga feels content. The boy calls her "Mistress, " and she believes he is the key to her newfound happiness. She is ready to protect him at any cost. What she does not foresee is how quickly pride, jealousy, and forbidden knowledge can spiral beyond control - and how dangerously fate can turn against them all. Who would have thought that the curious boy would free the terrible Callugar from his prison cell, a creature that even the witches trembled before? Just as it seemed that this would be the worst witches' sabbat of all time, Sajo would get the chance to prove his worth.