An interesting story, but Mary Sue aspects are inescapable.

*After days of training, the protagonist is stronger than the strongest witches who have ever walked this planet.

*She's always right, and profoundly flawless, just because.

*Anyone she meets will go out of their way to help her.

*Anyone she meets who doesn't instantly start helping her is profoundly evil.

*Effortlessly overcomes any obstacle or opponent.