Witchings by Ortega

Every year, in the magical town of Ravenskill, Witchlings who participate in the Black Moon Ceremony are placed into covens and come into their powers as full-fledged witches.

And twelve-year-old Seven Salazar can't wait to be placed in the most powerful coven with her best friend! But on the night of the ceremony, in front of the entire town, Seven isn't placed in one of the five covens. She's a Spare!

Spare covens have fewer witches, are less powerful, and are looked down on by everyone. Even worse, when Seven and the other two Spares perform the magic circle to seal their coven and cement themselves as sisters, it doesn't work! They're stuck as Witchlings—and will never be able to perform powerful magic.

Seven invokes her only option: the impossible task. The three Spares will be assigned an impossible task: If they work together and succeed at it, their coven will be sealed and they'll gain their full powers. If they fail... Well, the last coven to make the attempt ended up being turned into toads. Forever.

But maybe friendship can be the most powerful magic of all…