Now that the The Flash/Arrow crossover is in the books, both heroes have returned to their respective cities. Next week brings the final Arrow episode of 2015, Dark Waters, airing Wednesday, December 9 at 8 PM ET on The CW. Today, the network has released a trailer for Season 4's fall finale, which reveals that Damien Darhk (Neal McDonough) is back on the warpath, targeting both the innocent civilians of Star City, and someone very close to Oliver Queen (Stephen Amell).

After the city is attacked again, Oliver Queen makes a bold move against HIVE. Malcolm (John Barrowman) checks in on Thea (Willa Holland) and leaves her with a warning. Things take a horrible turn when Damien Darhk (guest star Neal McDonough) retaliates in a brutal manner at Oliver's mayoral holiday party. This new trailer also teases that Darhk has kidnapped Felicity, in an episode that "will leave you breathless."

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While it seems unlikely that Felicity may actually die in the midseason finale, stranger things have certainly happened in Star City. At the end of Season 3, Oliver and Felicity both left Star City, with the hopes of beginning a new life. But the beginning of this season revealed that Oliver could never truly leave behind his past as the Arrow, returning to Star City when Diggle, Thea, and Laurel asked for his help. Since Oliver was ready to give up his vigilante ways entirely for Felicity, her loss could be too much for Oliver to handle, but we'll have to see how this episode plays out.

Interestingly enough, we learned in October that Neal McDonough's Damien Darhk will also cross over into The CW's The Flash and DC's Legends of Tomorrow, although it isn't known exactly when he will show up. Executive producer Marc Guggenheim also confirmed last month that Colton Haynes will make his return to Star City as Arsenal, in this season's 12th episode, which doesn't have a confirmed air date at this time. We still don't know why Arsenal is coming back, but he hasn't been seen since the Arrow Season 3, when he gave Thea (Willa Holland) his Arsenal outfit, before leaving town.

Other new additions this season include Alexander Calvert as Anarky, Echo Kellum as superhero Mister Terrific, Jimmy Akingbola as the villainous Baron Blitzkrieg, Jeri Ryan as Jessica Danforth, JR Bourne as Double Down and Rutina Wesley as Lady Cop. Do you think next week's midseason finale could provide another shocking twist? Or do you think Felicity will make it out alive? Chime in with your thoughts after checking out this new video.