The Salamander Spell (Tales of the Frog Princess Prequel)
by E.D. Baker
Grassina has always lived in the shadow of her perfect older sister, Chartreuse, whether it's being one step behind in lessons or getting the leftover suitors when Chartreuse deems them unworthy. But when Chartreuse seems unable to attain the magical skills that would make her the Green Witch and the kingdom of Greater Greensward is in terrible danger, it is Grassina who finds in herself the strength, clever thinking, and magic to set things right, defeating all manner of creatures including a pack of terrible werewolves.