Wicked Witch, meet the Black Fairy.
As Once Upon a Time's latest big bad (played to delicious perfection by guest star Jaime Murray) continues to skulk about Storybrooke in preparation for the final battle, she's begun to set her sights on Zelena (Rebecca Mader). And as this sneak peek at Sunday's episode, exclusive to E! News, proves, she's got an offer that we're worried Zelena won't refuse—no matter how much her relationship with Regina (Lana Parrilla) may have improved.
"I came here because I heard you were wicked and I thought we could help each other," the Black Fairy tells Zelena after sneaking into her cabin and momentarily terrifying her by taking her baby from her crib.
"Why would I help you?" Zelena asks, sneering, after grabbing Robin back from her clutches.
"Isn't it obvious? Look around," BF replies. "You're out here, living alone, in the middle of nowhere. You look like you could use a friend. Especially with the final battle approaching. I could be that friend. One wouldn't want to be alone for what's coming."
And while it may seem like the fear here is that Zelena will given in to the wickedness of it all, the true challenge to her and Regina's relationship will be when she decides to take on the Black Fairy on her own and put a stop to her, once and for all—despite Regina's wishes.
Meanwhile, in a flashback, we'll get to meet a familiar-looking young woodcutter (Tin Man, is that you?!) who has been cursed and turns to Zelena for help finding a new heart. She'll be forced to choose between keeping her powers and her friendship with him. And back in Storybrooke, the Charmings disagree over Emma (Jennifer Morrison) and Hook's (Colin O'Donoghue) wedding plans. Hey, at least you'll all be awake at the same time for it, Charmings!
Once Upon a Time airs Sundays at 8 p.m. on ABC.