Oliver Queen (Stephen Amell) will get more than what he bargained for in the upcoming midseason finale of the hit The CW series "Arrow."

In "Dark Waters," CarterMatt reports that Oliver is out to take revenge on HIVE after the brutal attack against the city. Damien Darhk (Neal McDonough) will take this as a declaration of war, and he will hit Oliver where he is most vulnerable. The villain will go after the superhero while he is hosting a holiday party. With most of his family and friends present, viewers can expect that there will blood shed after Damien is done with his retaliation.

Damien will not be the only one to cause trouble for Team Arrow. A new bad guy is about to be unleashed in Star City and he means business. According to TV Line, The Calculator will appear in season 4. Tom Amandes has been tapped to play the DC villain who is described as a bit of a super genius and criminal mastermind. He would bring with him a returning character, Roy Harper (Colton Haynes).

Harper aka Arsenal left the show in Season 3 after faking his own death in prison. He took the fall for Oliver as the masked vigilante known as the Arrow. The website revealed that The Calculator would be using his powers to blackmail Harper out of hiding in order to do his bidding in Star City.

Meanwhile, a recent spoiler report from TV Line disclosed that Nyssa (Katrina Law) is biding her time for her confrontation with Malcolm Merlyn (John Barrowman). Showrunner Wendy Mericle confirmed the character would be coming back as she has unsettled business to finish.

"Nyssa's stories are far from wrapped up. She's in Nanda Parbat, she's been arrested in the wake of destroying the Lazarus Pit, and she has a score to settle with Malcolm Merlyn. We don't intended to leave anyone hanging, including her!" the executive producer said.

"Arrow" season 4 midseason finale will air Dec. 9 at 8 p.m. EST on The CW.