The CW is expanding its fictional superhero universe featuring characters from the DC Comics with the release of "DC's Legends of Tomorrow." The show will begin with strong attribution to the characters from the other two superhero series in the network. 

The 15-episode spin-off series will feature several characters from both "Arrow" and "The Flash," who are gathered by Rip Hunter (Arthur Darvill) and must all work together to bring Vandal Savage's (Casper Crump) evil plans to an end.

Since the group is composed of individuals who are either friends or foes, series showrunner Phil Klemmer revealed how they managed to combine the characters without having to cause a bloody riot whenever they share the same room together.

"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," Klemmer told The Hollywood Reporter during the 2015 San Diego Comic-Con. 

Meanwhile, the show's other executive producer, Marc Guggenheim, said that he persuaded the writers of the upcoming series to read the 2001 comic book titled "Time Masters: Vanishing Point" by Dan Jurgens. The plot of the comic book discusses several important rules about the proper ways to time travel. 

According to Guggenheim, one of the time travelling rules mentioned in the book is it's a bad idea to leave anything behind since something that clearly does not belong to a certain timeframe could greatly change the timeline, thus resulting to big chaos.

Guggenheim also said that the upcoming DC TV series will feature elements from "Justice League International" written by Keith Giffen and J.M. DeMatteis. This could mean that the show will have a slightly comedic tone. 

On the other hand, Klemmer said that the upcoming series will look something like "Ocean's Eleven" or "Dirty Dozen," in which a group of opposing anti-heroes have to work together for a common goal. 

Filming for "DC's Legends of Tomorrow" is slated to begin this year. The show is expected to debut in 2016.