‘Legends Of Tomorrow’ Spoilers: 6 Things To Know About 'The Flash’ And ‘Arrow’ Spinoff Before The Jan. 21 Series Premiere

The DC Television Universe is going to get a little bit bigger. “Legends of Tomorrow,” DC’s third drama on the CW, launches Thursday, but this will be a little different than "Arrow" and “The Flash.” The show takes eight characters that DC fans were introduced to on the previously mentioned dramas and teams them up to travel through time. White Canary (Caity Lotz), the Atom (Brandon Routh), Captain Cold (Wentworth Miller), Heat Wave (Dominic Purcell), Hawkgirl (Ciara Renee), Hawkman (Falk Hentschel), Dr. Martin Stein (Victor Garber) and Jay Jackson (Franz Drameh) will work together to travel through time and take down a major villain. With so many super powered characters, expect the show to get a little complicated. Here’s what you need to know about “Legends of Tomorrow”:

1. The New Villain – The Legends are trying to defeat Vandal Savage (Casper Crump), the villain introduced in December’s “Flash”-“Arrow” crossover. The immortal being has a powerful army and is a threat to humanity.

“He's totally out of his mind,” executive producer Phil Klemmer revealed to TV Guide. “He's totally cruel and sadistic. He's got a Messiah complex. Once we get into his underlying logic for why he's doing what he's doing, that's a super interesting turn we can reach by the end of the season.”

2. Time Travel Rules – As with any decent sci-fi show, there are rules. Time is a tricky thing and it can’t be messed with too much. If the Legends alter the wrong event, they could change history. However, they’ll have a little time to fix their mistakes.

“Time is concrete that starts to set,” Klemmer explained to Entertainment Weekly. “The longer the consequences of that event play out, and once the events of the future are set like concrete, then it’s impossible to change them.”

However, they won’t be able to revisit a time and place they already saw and changed. Crossing over with their own timelines has “catastrophic” effects.

3. White Canary’s Journey – Becoming a trained assassin and coming back from the dead is pretty traumatic, so it's safe to say that Sara has had a difficult road. And it isn’t surprising that the “Arrow” alum will be on a journey of self-discovery in the new series.

“Her journey on our show is basically learning that she’s more than just an assassin,” executive producer Phil Klemmer told EW, “which is a bit of a challenge because she was recruited by Rip for the fact that she is an assassin, and she is a cold-blooded killer, and she doesn’t hesitate when she’s ordered to pull the trigger, but she definitely has a personal journey that is at odds with her place within the team.”

Expect her to get a new love interest as well on one of her trips to the past.

Watch a “Legends of Tomorrow” Season 1 trailer below:

4. Fighting – The Legends won’t just fight the villains. They’ll fight each other. With so many heroes, there are a lot of leaders. It won’t be easy for them to work together.

“That’s, to me, the interesting and unique part of this series,” Garber told Variety. “You have this dysfunctional family all together and traveling through time and trying to combat the worst possible evil history has ever known. In every situation, every person has their own idea that they think is the best.”

5. Crossover Guests – What’s the fun of having three DC Universe shows if they can’t crossover? While major crossover events (like the “Flarrow” two-parter) haven’t been announced, a few favorites from Star City and Central City will visit “Legends of Tomorrow.” Barry (Grant Gustin) and Cisco (Carlos Valdes) from “The Flash,” as well as Oliver (Stephen Amell) and Laurel (Katie Cassidy) from “Arrow,” are scheduled to appear in Season 1.

6. More Comic Book Heroes – Though the show already has quite a cast of comic book characters, expect them to run into a few other famous names. Jonah Hex (Johnathon Schaech) will appear when the Legends travel back to the Old West, according to the Hollywood Reporter. Constantine (Matt Ryan) is also rumored to appear.

“Legends of Tomorrow” premieres Thursday at 8 p.m. EST on the CW.