When heroes alone are not enough … the world needs legends. Having seen the future, one he will desperately try to prevent from happening, time-traveling rogue Rip Hunter is tasked with assembling a disparate group of both heroes and villains to confront an unstoppable threat — one in which not only is the planet at stake, but all of time itself. Can this ragtag team defeat an immortal threat unlike anything they have ever known?

“Some of these characters might not make it for the full trip," says showrunner Phil Klemmer.

It began with the gritty and grounded Arrow, expanded to the realm of superpowers and time travel with The Flash, and now the CW superhero universe is about to get even wilder with Legends of Tomorrow.

The series, which features several stars from Arrow and The Flash, centers on Rip Hunter (Arthur Darvill) assembling a team of both heroes and villains to travel back in time to stop Vandal Savage.

“We made the present so screwed up and uninhabitable for these characters that they had to literally get onto a spaceship and go to another time just so they wouldn’t be killed either by their friends or enemies,” showrunner Phil Klemmer told reporters at Comic-Con.

Gearing up for an expected early 2016 debut, the series recently cast Danish actor Casper Crump in the role of immortal time-traveling villain Vandal Savage, and Reckless alum Falk Hentschel as DC superhero Hawkman. Although the trailer provides some clues to the story, there are still a lot of questions surrounding the series.

Here's one tantalizing hint: executive producer Marc Guggenheim told The Hollywood Reporter he’s encouraging the writing staff to read Dan Jurgens' 2011 comic book run Time Masters: Vanishing Point. "It’s a good series for its depiction of Rip Hunter and a crazy combination of characters," he said.

THR got seven more clues from Guggenheim and Klemmer at Comic-Con about what fans can expect.

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What is the show's tone?

“The show will contain elements of Keith Giffen and J.M. DeMatteis’ Justice League International run,” Guggenheim told THR. That's probably a reference to the show’s tone, as Giffen and DeMatteis’ run is considered more comedic than grim. Klemmer compared the show to Ocean’s Eleven or Dirty Dozen. However, he also said the show would eventually introduce darker elements like betrayal and characters being tempted by the dark side.

Hawkman will be more than 5,000 years old.

Hawkman will make his debut on The Flash and Arrow before making his way into Legends of Tomorrow. In the comics, Hawkman’s real name is Carter Hall and, like Hawkgirl, he has been reincarnated through the centuries. The producers said Hawkman will be 5,000 years old and will retain his memories of his past lives, whereas Hawkgirl (Ciara Renee) will not. Guggenheim wouldn’t reveal if Hawkgirl would be an alien from the planet Thanagar as she is in the comics, but he did say, “You’ll get a clear picture of what her origin story is and you’ll actually get a chance to see it. Fans of the comics will recognize an awful lot. It’s probably one of the more faithful origins that we’ve told.”

What are the rules of time travel?

Time Masters: Vanishing Point establishes a lot of time traveling rules. An idea brought up in the comics is not leaving anything behind, as it would contaminate the timeline. But the show is poised to leave more than say just a cold gun or even an A.T.O.M. suit in the past. “Some of these characters might not make it for the full trip," Klemmer said, adding that, "some might be lost in time."

It’s important for heroes to keep their identities a secret not only for themselves but for their loved ones, which is even more important for the time traveler. In the comics, Rip Hunter is actually an alias the protagonist uses so that his enemies won’t be able to go back in time and kill “Rip” at a younger age (read: Terminator).

Another idea brought up in the comics is Rip’s preference to use weapons from whatever time period he’s currently in, which works for White Canary (Caity Lotz) since she relies on hand-to-hand combat and a bo staff. In the comics, Rip uses modern/futuristic weapons in dire circumstances, so it’ll be interesting to see how the show handles Ray Palmers’ (Brandon Routh) suit, Captain Cold (Wentworth Miller) and Heat Wave’s (Dominic Purcell) guns, or even “the burning man” Firestrom’s abilities in archaic times.

The comics also reveal time travel is a two-way street. Serhattu is a villainous sorcerer from the caveman era who can communicate with sorceress Skyle from the future. He even tries to travel to the future from the past, which may or may not explain how Vandal Savage’s armed forces and giant robot are able to keep up with Rip and Co.

Booster Gold won't appear in season one.

In comic book lore, DC fan favorite Booster Gold is Rip Hunter’s father. Booster is one of two notable characters from the 25th century, the other being Eobard Thawne (Tom Cavanagh) aka the Reverse-Flash. “I wish I could tease a Booster thing but, you might have to wait a good long while at least on our show,” said Klemmer. “Perhaps Booster is being groomed for bigger things." Could that mean he's being saved for a DC/Warner Bros. movie?

That mystery character is not a superhero.

Franz Drameh was cast as Jay Jackson for Legends, leaving the DC faithful scratching their heads as to who he is. Described as a former high school athlete who was injured in a debilitating accident, Jay isn’t the name of a preexisting character in the DC Comics. Klemmer only had this to say: “Jay Jackson is not code for any other DC superhero.” Which means he could be an original character similar to that of Gotham’s Fish Mooney (Jada Pinkett Smith).

Will there be an opening monologue?

Time Masters: Vanishing Point features something very familiar to viewers of Arrow and The Flash: an opening monologue explaining who the protagonist is. It isn’t difficult to imagine Legends of Tomorrow will have a similar format, possibly even pulling lines directly from the source material itself.

Will Zoom or Reverse-Flash show up in Legends of Tomorrow?

It’s worth noting that Professor Zoom, the big bad of The Flash's second season, shows up at the end of Time Masters: Vanishing Point. Although Eobard Thawne was wiped out of existence at the end of The Flash season finale, given the cross-pollination nature of the show with Arrow and The Flash, it isn’t outside the realm of possibility that Professor Zoom or the Reverse Flash could show up in Legends. Especially when you consider that in The Flash season finale, Dr. Wells referenced an encounter with Rip Hunter.

Legends of Tomorrow debuts midseason on The CW.