Arrow-Flash Crossover: Expect 'Seismic Change' and Special Effects in Tonight's Conclusion

Damian Holbrook
Flash and Arrow Crossover
Katie Yu/The CW

The heroes of The Flash and Arrow are really getting their feathers ruffled in this week's two-part crossover. Not only did they see Cisco's new flame Kendra Saunders (Ciara Renee) "emerge" as Hawkgirl during The Flash last night, they met a wild new villain and Oliver Queen (Stephen Amell) saw someone he suspects might be that kid of his we all learned about in Season 2 of Arrow. In addition, there were enough action set pieces and storylines established for tonight's conclusion that we no longer doubt Arrow executive producer Marc Guggenheim's claims that this year's event is "so much bigger than last year...it really feels like a two-hour movie over two nights.”

So far, the mega-story has found Barry (Grant Gustin) and Co. sort of battle-befuddled by Vandal Savage (Casper Crump), an immortal killer out to exterminate Kendra. “He clearly has something mystical about him,” says Andrew Kreisberg, an executive producer on both shows. But the Flash squad is “used to science and metahumans; dealing with things mystical and ancient is what Oliver [Stephen Amell] and his team do. So they all [skedaddled] to Star City for help.”

RELATED: 7 Multi-Episode Crossovers That Made for Great TV (PHOTOS)

Flash-Arrow Crossover: Kendra, Cisco and Carter

Diyah Pera/The CW

Kendra, Cisco and Carter

Once there, it became clear Savage wasn’t the only one hunting Ms. Saunders, who soon learns that she’s an oft-reincarnated superhero warrior from a winged hottie who just so happens to be Kendra’s soulmate and fellow Legends character, Carter Hall, aka Hawkman (Falk Hentschel). “She has no idea that she is a character in a spinoff show!” jokes Kreisberg, adding that "everything that happens in the crossover happens because Kendra is in danger." It also happens to be serving as a nice set-up for the midseason spinoff, DC's Legends of Tomorrow, which will feature Kendra, Carter and Vandal. "It's a little bit of a proto-pilot for Legends."

After what Guggenheim called a jaw-dropping cliffhanger on The Flash, the events move tonight to Arrow, where Carter and Kendra’s origin story and Savage’s reign of terror with the Staff of Horus won’t be the only action Oliver and friends must deal with. Not to spoil anything, there is some heart-achingly emotional work by Amell and Emily Bett Rickards (Felicity), a massive fight scene featuring pretty much every active character in the Arrowverse, and a cinematic effects sequence that will quite literally leave you wondering if you just saw what you think you saw. “We do something I don’t think anyone is going to anticipate,” Guggenheim teases. “One of the biggest seismic changes we have ever done happens in the Arrow half of the crossover.”

For fans wondering about the season premiere’s flash-forward casualty, that is gravely concerning.

 Arrow airs tonight, Wednesday, Dec. 2, 8/7c, on The CW