SPOILER WARNING: This article contains major spoilers for "Crisis on Infinite Earths, Part 3," the third installment of this year's Arrowverse crossover.

"Crisis on Infinite Earths" has just introduced a new hero into the Arrowverse.

There have been many cameos throughout The CW crossover event, but one of the most surprising comes in the form of Tom Ellis' Lucifer Morningstar.

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Mia Smoak, John Diggle and John Constantine pay Lucifer a visit on Earth-666. They need help in finding a way to Purgatory to rescue the soul of Oliver Queen, who died in the first chapter of "Crisis on Infinite Earths."

Lucifer passes a devil playing card to Constantine that will grant them access to Purgatory. However, once the image on the card fades away, their souls will be stuck there as well. Once Lucifer departs, Constantine uses the card to teleport the trio to Purgatory.

Helmed by Joe Henderson and Ildy Modrovich, Lucifer’s fourth season stars Tom Ellis as the Devil, Lauren German as Det. Chloe Decker, D.B. Woodside as Amenadiel, Rachael Harris as Dr. Linda Martin, Kevin Alejandro as Det. Dan Espinoza, Lesley-Ann Brandt as Mazikeen Smith, Aimee Garcia as Ella Lopez. The show's fifth and final season is slated to premiere on Netflix in 2020 and will be split into two parts.

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"Crisis on Infinite Earths" will return after the winter hiatus. The crossover will conclude on Tuesday, Jan. 14 in Arrow at 8 p.m. ET/PT and in DC's Legends of Tomorrow at 9 p.m. ET/PT.