This TV season’s four-way crossover event between “Arrow,” “The Flash,” “Supergirl” and “Legends of Tomorrow” is the CW’s “most ambitious” crossover yet.

During a phone interview with Entertainment Weekly’s SiriusXM radio show Superhero Insider, “Arrow” and “Legends of Tomorrow” executive producer Marc Guggenheim explained how the upcoming week-long special event is different from the crossovers that the network aired in the last two years.

“I think it’s massively different,” Guggenheim said. “The first crossover we did was two separate storylines that had a slight tangential connection to each other. Then last year, the crossover we did was a two-parter that told one complete story with a beginning, middle, and end across ‘Flash’ and ‘Arrow,’ but it also had the work of setting up ‘Legends of Tomorrow.’”

“This year, we’re doing by far the most ambitious crossover we’ve ever done,” the exec producer continued. “It’s basically a huge three-part story that also brings in Supergirl [Melissa Benoist], so it’s crossing over all four shows. It’s telling one big epic movie of a story.”

Although the mash-up event isn’t setting up a new show, Guggenheim said that the upcoming crossover won’t fall short in action and drama.

“It’s just big, bombastic, huge action [and] there’s also some really poignant character moments,” he said. “There’s a lot of plot lines, particularly I would say in ‘Flash’ and ‘Legends,’ that come to fruition in the crossover.”

“I want to say it’s by far one of the most ambitious things anyone in network television has ever attempted,” he added of the crossover. “It’s completely insane.”

Guggenheim revealed last month that the CW’s DC Comics TV heroes will all team up to defeat the alien race Dominators in the crossover.

“This year, for our mega ‘Arrowverse’ crossover, we’re taking inspiration from a DC crossover from the late 1980s known as ‘Invasion!’ which featured … the Dominators, who’d previously, vexed the Legion of Superheroes,” he said (via Entertainment Weekly).

In the comics, the Dominators believe that the unpredictable evolutionary tendencies of Earth’s metahumans pose a great threat to the state of the universe. In one of their attempts to invade Earth, a Dominator created a Gene Bomb and detonated it in the planet’s atmosphere, affecting many people with the metahuman gene and causing them to lose control of their powers and eventually fall into a coma and die.

Guggenheim told Superhero Insider that the Dominators have a very similar mission in the crossover. “I will say that their goal is very closely related to what was established in the comics, and it does have to do with metahumans,” Guggenheim confirmed.  “It’s very, very faithful to the comics.”

Meanwhile, Kevin Smith — who has directed a couple “The Flash” episodes — shared two weeks ago that seeing the script for the crossover event made him even more excited for the week-long special.

“I’ve seen what they’ve got planned for the massive event, and it f— king RULES!” he wrote on Instagram. “It’s breathtaking in its enormity and will be particularly fun for any long term @dccomics fan like me who has been reading that company’s books for decades. They’re pulling elements from a story that was a favorite of mine back in the day so there are tremendous terms and legendary locations in the crossover script I saw that will make any #dccomics lover fill their Undergoes!”

The four-way crossover will air sometime this fall.

CW’s DC TV Shows Marc Guggenheim said that this TV season’s four-way crossover event between “Arrow,” “The Flash,” “Supergirl” and “Legends of Tomorrow” is CW’s “most ambitious” mash-up episodes yet. Photo: The CW