As National City faces a new wave of villains, including Lena Luthor's far-reaching machinations against Supergirl, the Girl of Steel fights a new foe on home turf in a new promo.

The CW has released a sneak peek at Season 5's seventh episode, titled "Tremors," with guest star Mitch Pileggi portraying an enemy with advanced longevity and powers astonishing even Brainiac 5. After preparing for a showdown, Kara introduces the sinister villain to Kryptonian conditions in what appears to be the crystalline Fortress of Solitude.

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A previously released synopsis by the network teased that Kara would finally learn about Lena's personal vendetta against her while J'onn J'onnz would discover his long-lost brother Malefic's whereabouts.

Lena had been secretly plotting against Supergirl for much of Season 5, after learning her secret identity from her older brother Lex in the Season 4 finale. Feeling betrayed by the longstanding deception, Lena has orchestrated much of Kara and DEO's recent struggles as part of her elaborate revenge.

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Airing Sundays at 9 p.m. ET/PT on The CW, Supergirl stars Melissa Benoist as Kara Danvers, David Harewood as Martian Manhunter, Mehcad Brooks as Jimmy Olsen and Chyler Leigh as Alex Danvers.