Mary Margaret (Ginnifer Goodwin) and Regina (Lana Parrilla) are set to go to battle with each other on the next episode of ABC's Once Upon a Time, bringing out each of their dark sides.

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Goodwin recently spoke with TVLine about next week's episode, titled Shattered Sight, which features the residents of Storybrooke living under the Snow Queen's (Elizabeth Mitchell) evil spell. The actress teased the return of "Dark Snow" in the episode.

"It's really wonderful, because Regina comes back [to the sheriff station] as her full Evil Queen self. But instead of it being that they fall into their old dynamic, it's more that the Evil Queen battles Dark Snow, from those episodes where Snow White was under dark enchantment," Goodwin said.

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She said that these two energies combined make for hilarious results, adding that she could have filmed this episode "every day forever."

"For her to come back in her Evil Queen regalia is hilarious, because she's so not that person anymore," Goodwin said, of Regina. "And there's something about being Dark Snow in Storybrooke that we also found very funny, because it's so not the woman that she has become."

Mary Margaret ends up jabbing Regina for using her magic fireballs, persuading her to fight "man-to-man" with swordplay.

Going beyond this episode, Goodwin also revealed that she will have more to do in the second half of the season, though she did not tease anything specific. She did admit, however, that it will definitely be "worth the wait."

Once Upon a Time airs Sundays at 8 p.m. ET/PT on ABC.

Watch the promo for the next episode of Once Upon a Time below:

Tags: Once Upon A Time television ABC