New revelations were unveiled about Season 4 of "Arrow" at Comic-Con in San Diego, including teasers about upcoming crossovers with "The Flash," Oliver's new Green Arrow costume, and Oliver and Felicity's romance.

During "The Flash" press roundtables, "Arrow" executive producer Andrew Kreisberg confirmed that fans will be treated to more mini-crossovers between "Arrow" and "The Flash" in addition to a major one in December.

"We do have crossovers planned, both Episodes 8's again, this year, which will air in December. It's a 2-part crossover, which starts on 'Flash' and ends on 'Arrow,' and that's sort of the big crossover event," said Kreisberg, according to Cinema Blend.

"Arrow" fans were also treated to a special peak at Oliver's new costume when series star Stephen Amell performed a soliloquy while wearing a brand new suit at Comic-Con.

Plus, the SDCC panel teased guest appearances from minor Batman villain/ally Anarky and Justice Society member, Mr. Terrific.

While speaking to TVLine's Michael Ausiello, actor John Barrowman teased that the Season 4 premiere will leave fans in shock: "[It's] one of those episodes where, [when] watching, you're gonna go, 'What?!?!"

"Especially the last scene," added Paul Blackthorne, who plays Det. Quentin Lance on the show. "That last scene is gonna haunt the rest of the season."

Executive producer Wendy Mericle also previewed the arrival of Neal McDonough's Damien Darhk as the new big bad of the season, revealing that unlike previous villains, "Damien doesn't have any code. He's just pure evil."

Marc Guggenheim dropped hints about what to expect from Damien Dahrk, saying, "He's a very different kind villain. Malcom, Shae and Ra's, they were all guys who did the wrong thing for what they thought was the right reason. Damien doesn't care about morality. We wanted a big bad who is really pure evil." However, he does maintain "a sense of humor."

Although Mericle didn't drop any major spoilers about Oliver and Felicity's romance, she did suggest that there is a possibility that viewers will get to see how they spent their time together in seclusion.

Meanwhile, actor Emily Bett Rickards opened up about her character, revealing that she hopes Felicity will return to being happy and funny in the new season, instead being sad and weepy like in Season 3.

"She felt like she was crying a lot. I feel like she went through a year that wasn't necessarily her favorite," said Rickards, according to io9.

"I feel like she lost a little bit of her strength to a certain extent. I think she got burned a couple too many times, and then found herself in situations she wasn't exactly sure she wanted to be in or if she was being true to herself between Ray [Palmer] and between Oliver [Queen], and if she was giving enough time to what she truly wanted. And then we throw her mom in there. And we get mom to really tell the truth. And that's kind of what happens, and you end up sobbing."

When asked if viewers will see a stronger Felicity in Season 4, Rickards responded, saying, "That's my hope and the plan and, hopefully, she gets funnier again because I don't want to see her crying all of the time. It was a big disappointment to me to have her crying a lot because one thing I love about Felicity so much is that she's so strong and independent and sticks to her guns and is true to herself. And that is something I admire about her. I think she was true to herself last year, but I just don't know if she necessarily knew what she was doing was authentic and she was trying to find it."

Furthermore, Den of Geeks revealed that the show is looking to cast a big name to play "a mayoral candidate who is deeply committed to her city and willing to risk her life to stand up for the people." The character is described as "a female in her 50s, early 60s ... a peer and an old friend of the late Moira Queen and was once close with Oliver and Thea. She is also a mother, and cares for her daughter above all else."

Episode 1 of Season 4, which is titled "Green Arrow," will premiere on The CW on Wednesday, Oct. 7.