[DrMoreau]

So fan fiction style scenario that doesn't involve changing the ending.

Remember they only put her back in the ground, and she was raised by a very simple spell.

Martin and everyone leave.

The girl with the hair band misses her power, she was like her apprentice, her heart already and permanently corrupt. Maybe a few more for a coven like thing, but it could be just her.

They raise Griswalda (Ms. Dorey) back up, and now noticing she drew the center's attention she casts a spell to keep the school shrouded in the future.

She begins to bill it as an exclusive boarding school, looking for girls with actually strong minds and wills, as they tend to break out of the zombie-like state sooner and make more powerful witches. That sort of breaks the trope a bit too.

They come to the school, are not immedietly turned, but instead the students enjoy the new girls for a bit, like freshmen hazing. They are prevented from outside contact.

The classes would be centered around evil magic, like a twisted Hogwarts, freaking these freshmen out.

Once they've gone through their hazing, or as they get closer to the truth, they are turned one by one, so their new attitudes can be rubbed in the other girls faces as they join the "other students".

Until they all are corrupted, ready to absorb their black magic training, and they get some new transfers into the freshmen class.

Eventually Griswalda will have enough fully trained witches to ensure the center doesn't bother them again, and reclaim Diana, who Griswalda is irked at loosing.