Rumple said, “My vault is for the darkest of magic that even i don’t often understand.” Something along those lines.
I could also see them combining Elsa and the White Witch from Narnia. I really hope they do this and we go to Narnia next!
Combining it could also explain why Rumple would locked her up. In the books Jadis created a spell which was able to destroy her entire homeworld Charn and killed everyone inside of it except of herself just because she was loosing the fight against her sister for the throne of Charn.
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