A handful of new villains from Earth-X are about to crash Barry and Iris' wedding. The latest promo for the crossover between ArrowThe FlashSupergirl and DC's Legends of Tomorrow focuses on these Big Bads, who bear an uncanny resemblance to the heroes of Earth-1.

"Everyone you care about, everyone you love, they're gonna die," an ominous voice intones over the montage of explosions and marching troops.

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The promo offers a few tantalizing glimpses of the crossover, including a shot of Prometheus, Iris and Barry hugging on the Waverider, Cisco fleeing an explosion in a church and a white-haired Caitlin Snow flinching from the blast. In one scene, Green Arrow leads Flash, Supergirl, White Canary, Firestorm and Alex Danvers down a hallway in STAR Labs. Towards the end of the trailer, Earth-X's Oliver Queen -- decked out in an SSR uniform -- aims a gun off-camera and Killer Frost knees a soldier in the face.

This year’s four-part crossover will air across two nights, beginning Monday, Nov. 27, with Supergirl and Arrow (on a special night for one week only), and concluding Tuesday, Nov. 28, with The Flash and Legends of Tomorrow.