Board Thread:Spoilers!/@comment-27060727-20170106065555/@comment-25926288-20170407184459

Well, it lined up to be her. Blue knew about a dark curse capable of traversing to the LWM, Black Fairy has a wand capable of performing every spell ever casted, and she's also the Dark Fairy (Dark Fairy dust person as she gave it to Snow (assumption) and Gideon (that's how he turned Queenie into a snake).

Rumple just needs to be more specific though. Besides that, it seems as though she only touches other worlds briefly before the big hand of doom drags her back to her prison. (Which is hilarious that Blue is capable of such powerful magic yet....)