There's a lot to be excited about in "Arrow" season 4. Oliver is going green, Diggle gets a helmet and a codename, Team Arrow upgrades their headquarters, Constantine is set to reappear, and a whole lot more. Fans will get an idea how all this will look like in a trailer, which is apparently going to be epic. 

Executive producer Wendy Mericle is "pretty sure this trailer is going to break the internet." She tweeted this after her fellow EP Marc Guggenheim informed fans via Twitter that a rough cut of the preview was ready and that they were blown away by it. 

Unfortunately, both of them were coy as to when this trailer will be released. The wait won't be very long, however, as the DC Comics series adaptation is close to premiering and the trailer is already prepared. 

There are a lot of elements that can make it to the trailer. It can give a glimpse of Mr. Terrific and Anarky, two of the many new characters from the comics joining the show. It will most likely show Damien Darhk, the latest and most dangerous threat to Star City (previously Starling City). It is also expected to give fans a peek at Diggle rocking his new suit and Oliver in action with his spruced up costume. Whichever rudiments end up composing the "Arrow" season 4 preview, fans are assured they won't be disappointed.

In other related news, there's the question of Felicity getting her own codename, too. Every member of Team Arrow is going by a moniker now, even Diggle. But not the IT expert – Mericle has an explanation for this. 

"Dig is out in the field, so there's a necessity for [him to have one]," Mericle told TV Line. "But not quite yet for Felicity, although you never know. We all love the idea of her getting her out there more ... It's just a question of finding the right way to do it." 

"Arrow" season 4 airs Oct. 7.