With "Crisis on Infinite Earths" coming to the Arrowverse this fall, each panel for The CW's DC TV series at San Diego Comic-Con on Saturday had some stunning reveals about what fans can expect from the multiverse-altering event set to rock Arrow, The Flash, Supergirl, Batwoman, and DC's Legends of Tomorrow in December and that is especially true for The Flash. During the show's panel on, showrunner Eric Wallace revealed that Tom Cavanagh will be appearing in "Crisis" as Pariah.

"As part of 'Crisis on Infinite Earths' crossover, not only will Tom be playing the two character we heard here, he will also be playing Pariah as part of the crossover," Wallace revealed. "He works for the Anti-Monitor."

"In the original miniseries, it's Pariah who is very much integral in releasing the Anti-Multiverse," he continued. "For Tom to play such a pivotal character... it's just going to tear your guts out and make you cry." The reason behind Cavanagh's new role, which will be revealed at the end of the first "graphic novel," will "lead up to a very, very big twist at the end of the Bloodwork case that launches 'Crisis."

For fans of the 12-issue comic book limited series of the same name that The CW's "Crisis" is adapting, Pariah is a huge reveal. In comics Pariah (real name Kell Mossa) is one of his Earth's greatest scientists and it's his unorthodox experiments to view the universe ends up allowing the Anti-Monitor to discover the existence of his Earth and then destroy it with waves of anti-matter. Pariah survives thanks to the Monitor and ends up with the ability to travel from one Earth to another. Because of this, he's forced to watch world after world after world die. During Crisis, Pariah blames himself for the death of his own world but is ultimately told that he is not to blame. The Anti-Monitor reveals that his scientific experiments didn't actually unleash the energy to destroy universes, he simply opened an antimatter portal that the Anti-Monitor then converted the energy, and thus destroyed Pariah's world. At the end of Crisis, Pariah and Lady Quark, whom he rescued from Earth-6, ask Harbinger to join them in exploring a new, reformed earth.

This reveal that Cavanagh will have a seemingly major role in "Crisis" joins some other significant updates about the crossover. Brandon Routh, who currently appears as Ray Palmer in Legends, will return as Superman for the event, specifically as the Kingdom Come take on the character. Burt Ward, who played Robin in the iconic 1960s Batman TV series is also set to appear, though his role is uncertain at this point. Arrow's Stephen Amell will be playing multiple versions of his character, Oliver Queen, and Supergirl's Lex Luthor (Jon Cryer) will also be appearing in "Crisis", another major surprise considering the character died at the end of Supergirl Season 4.

At this point, it almost seems to go without saying that "Crisis" is going to be a huge event for the Arrowverse and the Pariah announcement today confirms what Arrow producer Marc Guggenheim told ComicBook.com in that the event would have some very true-to-comics moments.

“Basically, we’re gonna begin — this is an exclusive — we’re gonna begin the way Crisis on Infinite Earths the comic begins, which is the destruction of various parallel universes. And the goal is for us to adapt key moments from the comic, those seminal moments,” Guggenheim told us.

“In fact, yesterday I pitched to the network what the story was going to be and the best part of the pitch, we have a board that DC made up for me, which is covers from key issues of Crisis on Infinite Earths. And we’re like, ‘We’re gonna do our version of this, we’re gonna do our version of this, we’re gonna do our version of this.’ Our goal is, the thing we’ve been saying, is we’re going to make a list of a 100 cool things that we want to do. And even if we only get to do 50, we’re still doing 50 cool things.”

The Arrowverse’s Crisis on Infinite Earths launches in December on The CW.