The Last Witch of Oz by Mae Holloway

FOUR YEARS AFTER DOROTHY…

Nineteen-year-old Tippetarius is a carnival thief—and a good one. Yet life on the road has left her yearning for roots and an honest calling.
But the moment Tip convinces herself to reach for something better by confessing her feelings for her knife-throwing best friend, her plans are waylaid. A stranger appears and, after informing her he wishes to right an old wrong, he presents Tip with a golden key, the handle of which bears the shape of two letters: OZ.
When Tip uses the key to escape kidnapping, she is transported to a wild land where sorcery is illegal. Something she doesn’t discover until after she’s arrested for being a witch.

Forbidden or not, Tip’s newfound powers make her valuable to the cold and brooding Scarecrow King of Oz, who enlists Tip’s help in subverting a coup. One being organized by the ruthless head-swapping sovereign of a neighboring realm. The same vain princess who would love to have Tip’s head in her collection.