SPOILER WARNING: This article contains major spoilers for "In Search of Lost Time," the latest episode of Supergirl.

Supergirl isn't going to be able to punch her way out of the latest threat to National City. "In Search of Lost Time," the latest episode, paved the way for the Worldkiller called Pestilence -- and, if the cliffhanger ending was any indication, she has finally arrived.

Last week, Mon-El revealed that Supergirl and the Legion of Super-Heroes have a common enemy. As it turns out, Pestilence will go on to become the Blight, who destroys the planet Winath in the future. Considering this, Mon-El has begun to help the DEO track down Pestilence.

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As Winn began to search for Pestilence, Mon-El offered a clue: plagues of Biblical magnitude herald her arrival. Winn was quickly able to track one of these down, but it occurred almost halfway across the globe. In the arctic, they discovered a river of blood flowing down an iceberg.

However, the second Biblical phenomenon happened a lot closer to home. At the end of the episode, Mon-El and Supergirl sought to escape the drudgery of training for a while by flying around the city. As they flew, pigeons began to drop dead out of the sky. The two quickly landed, only to look on helplessly as the dead birds began to pile up on the rooftop. This indicates that Pestilence has made her way to National City.

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Pestilence is the third and final Worldkiller, joining the previously introduced Reign and Purity. However, she may prove to be the most deadly, as Supergirl may not be able to beat her in a traditional fight. Judging by her name and the preview for next week's episode, Pestilence wields the power of disease, which means she can cause her enemies to fall sick. This seems to be the case for Kara's sister Alex and Winn, who appear hospital-bound in the next episode. It is unclear if Pestilence can use her powers against near-invulnerable Kryptonians and Martians, but she can certainly go after the people they love.

Airing Mondays at 8 p.m. on The CW, Supergirl stars Melissa Benoist as the Girl of Steel, David Harewood as Martian Manhunter, Mehcad Brooks as Jimmy Olsen, Chyler Leigh as Alex Danvers and Jeremy Jordan as Winn Schott, with appearances by Calista Flockhart as Cat Grant and Tyler Hoechlin as Superman.