"For comic book fans, everyone knows the Justice Society is really the precursor to the Justice League, so it's a pretty big move," executive producer Marc Guggenheim tells THR.

[Warning: This story contains spoilers from Thursday's season finale of Legends of Tomorrow, "Legendary."]

While the DC Comics films may be focusing on the Justice League of America, the DC TV universe is going further back in time to introduce the Justice Society of America, the very first superhero team-up ever published in comic books.

The CW's Legends of Tomorrow used Thursday's season one finale to reveal that Rex Tyler aka Hourman (Patrick J. Adams), along with the JSA, would be a major part of the Arrow/Flash spinoff's sophomore run. He arrived on a Waverider as the Legends team intended to take off as Time Masters, warning them that they would all die if they did.

"With his final words in the finale, he planted a pretty deep flag about where we're headed in season two, which is not just introducing Hourman but introducing his teammates in the Justice Society of America," executive producer Marc Guggenheim tells The Hollywood Reporter. "For comic book fans, everyone knows the Justice Society is really the precursor to the Justice League, so it's a pretty big move in our DC universe here on TV."

Although the DC Comics franchise keeps its film and television projects separate (unlike rival Marvel, which connects its film and TV projects in one shared universe), it's interesting to note that it's the newest — rather than the highest-rated DC show (Flash) — that is going to be the one introducing the iconic superhero team.

"God bless both the studio and the network. They've never said, 'This is too big. You can't do it,'" Guggenheim says. "They have often said, 'Jeez, this is so big, how are you going to do it?' They say that a lot. They're always asking us how the hell we're going to pull something off. Inevitably, our answer is, 'We literally have no idea. But we'll figure out a way.'"

The JSA was first introduced in 1940's All Star Comics #3, though it wasn't until the Silver Age of comics in 1961 that the JSA was retooled to become the Justice League of America. New rules were then set to differentiate the two groups: the JSA was established as the superhero team up from Earth-2, while the JLA came from Earth-1. This allowed for cross-pollination between the two universes and teams moving forward.

The introduction of Hourman and the JSA won't be the only reason Legends of Tomorrow will look different in season two. Along with some casting shakeups, the elimination of the Time Council and the set timeline takes away a huge part of the story and the rules that were established all season long.

"One of the other big things we've done in the season finale is we planted another flag in the form of Rip's [Arthur Darvil] statement. Because the Time Masters are essentially gone and the Legends have destroyed the Oculus, that all means that someone else has to do the job of the Time Masters," Guggenheim says. "Our Legends take that on as their new responsibility. It's sort of like, you break it, you buy it."

"That's really exciting to us, that our team of Legends, our misfits, are going to be responsible for the preservation of the timeline and protection of history," he adds. "As we've seen, our team, our guys are not always the most responsible people around so maybe time has got some new troubles. But it will provide a lot of fodder, a lot of fun story for season two."

While immortal tyrant Vandal Savage's (Casper Crump) story was definitively concluded in the season one finale, Guggenheim warns that season two's big villain is going to raise the stakes for the Legends team.

"The season two big bad is actually not going to be the [alien race of] Thanagarians," Guggenheim says. "It's going to be something else entirely. All I'll really say about the nemesis in season two is Vandal Savage looks like a walk in the park compared to what the Legends will be facing. This will be a much, much bigger threat. I'm going to leave it at that because when we do reveal it, it's going to be pretty big. People will be asking, 'Vandal who?' once they get the full picture of what our team is up against. It's going to be way bigger than what you can even imagine, I can guarantee it."

Legends of Tomorrow will return for season two on The CW.