I suspect that crystal/shard will be able to absorb her powers or something to turn it into an emerald. Not sure how that fits in with everything else though?
That makes sense. When we were introduced to Zelena in season 3 didn’t she have a necklace that made her more powerful and without it she would be powerless. I don’t know what ever happened to that or why she can continue to be powerful without it, but maybe she has to sacrifice some of her power to help bring down the black fairy.
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