Diane Duane

Sent on vacation to her aunt's home in Ireland, teenage wizard Nita becomes entangled in a magic battle to save the country from the ghosts of its past.

While Nita's sister and her dad host three young alien wizards, teenage wizards Nita and Kit travel halfway across the galaxy as part of an exchange program and find themselves again caught up in the dark doings of their nemesis, the Lone Power.

Thirteen-year-old Nita, tormented by a gang of bullies because she won't fight back, finds the help she needs in a library book on wizardry which guides her into another dimension.

Young wizards Kit Rodriguez and Nita Callahan manage to wangle their way onto an elite team sent to investigate the mysterious, long-sought "message in a bottle" that holds the first clues to the secrets of the ancient Martian race.

The long-running “cult favorite” YA fantasy series continues with a worldwide tournament of magic—from the author of A Wizard of Mars (Slate). 
 
Every eleven years, Earth’s senior wizards hold the Invitational: an intensive three-week event where the planet’s newest, sharpest young wizards show off their best and hottest spells. Wizardly partners Kit Rodriguez...

Scooby-Doo and the gang face off against festive frights, frosty nights, and the ghost of Christmas, who wants to wish everyone a scary Christmas! And the gang unwrap a series of mysteries in order to stop a group of chilling crooks from stealing the spirits of the season.