Once Upon A Time Meets Downton Abbey In Season 3 Special [SPOILERS] Before Mid-Season Premiere: Dan Stevens To Host 'Wicked Is Coming' As Zelena And Oz Debut!

As "Once Upon a Time" season 3 prepares for its mid-season premiere, spoilers confirm that a very special "Downton Abbey" cameo will occur in a one-hour special called "Wicked is Coming!"

According to E! Online, "Downton Abbey" alum Dan Stevens will host and be the voiceover for the special, which will recap the first half of season 3 and preview the upcoming arc.

Reportedly, "Wicked is Coming" will feature interviews with the "Once Upon a Time" cast, as well as with co-creators Eddy Kitsis and Adam Horowitz.

All of this will be leading up to the debut of Zelena, the Wicked Witch played by Rebecca Mader.

But Mader won't be the only new face to join "Once Upon a Time" season 3.

Spoilers by EW reports that actress Sunny Mabrey ("The Client List") will be joining Rebecca Mader in the second half of "Once Upon a Time" season 3. But while Mader is set to play the Wicked Witch, Mabrey will play the "elegant, warm, and benevolent" Glinda the Good Witch.

And finally, in addition to Rapunzel and Lumiere, it seems Hook will also get his own counterpart in the form of Blackbeard.

Spoilers confirm that actor Charles Mesure will portray the pirate.

"He is a pirate through and through, and he and Captain Hook do not have a love for each other, and the only thing two pirates will fight over -- even more than a woman -- would be a ship," Kitsis says to the Hollywood Reporter.

But if you're thinking we will go to Oz like Neverland, think again.

Spoilers confirm that while we will get a glimpse of Oz, it will not be the centerpiece of "Once Upon a Time" season 3 when it returns.

"The Wicked Witch is a big part of the second half and a driving force as an antagonist, but the world of Oz is not. It's a place that you will see and we'll spend a little bit of time there, but it's not an everybody-gets-on-a-ship-and-goes-there kind of thing," says Horowitz.