Bad Spelling (Book 1 of the Witches of Galdorheim) - The Witches of Galdorheim, #1

A klutzy witch, a shaman's curse, a quest to save her family. Can Kat find her magic in time?If you're a witch living on a remote arctic island, and the entire island runs on magic, lacking magical skills is not just an inconvenience, it can be a matter of life and death-or, at least, a darn good reason to run away from home. Katrina's spells don't just fizzle; they backfire with spectacular results, oftentimes involving green goo.
A failure as a witch, Kat decides to run away and find her dead father's non-magical family. But before she can, she stumbles onto why her magic is out of whack: a curse from a Siberian shaman. The young witch, accompanied by her half-vampire brother, must travel to the Hall of the Mountain King and the farthest reaches of Siberia to regain her magic, dodging attacks by the shaman along the way.