Following episode 7, "Arrow" season 8 will go on a winter hiatus. No new episode will air until next year. However, when the show returns the excitement will reach epic lengths.
The midseason premiere for "Arrow" season 8 will be the fourth chapter of the highly anticipated annual Arrowverse crossover "Crisis on Infinite Earths." The epic crossover that kicks off with "Supergirl" season 5 episode 9 on Sunday, December 8 will continue in its fourth hour with "Arrow" Season 8 episode 8 in January. The crossover that brings together heroes and the villains of "Supergirl", "Batwoman", "The Flash", "Arrow", and "Legends of Tomorrow" will conclude with "Legends of Tomorrow's" special episode.
Since "Arrow" episode 8.08 "Crisis on Infinite Earths: Hour Four" will air after the winter break, it is too early to expect the promo and synopsis. However, it is certain that the Green Arrow will take forward Monitor's mission to stop Anti-Monitor from destroying multi-verse.
Since the beginning of the eighth season of The CW series, The Monitor has been testing and strengthening Oliver for what is to come during the events of "Crisis." Whatever we have witnessed so far is setting up "Crisis."
Initially, it was thought that The Flash must sacrifice himself to stop the doomsday. However, very recently, unexpected twists in the events suggest that Oliver needs to die to stop the "Crisis." Given it is the final season of the series that set up the large Arrowverse, it is fair to assume that this must be Oliver's final journey.
Based on the comic book with the same name, "Crisis on Infinite Earths," the crossover will happen in five episodes in over two months wherein the DC superheroes and other cosmic powers will come together to fight the big bad Anti-Monitor, the evil counterpart and brother of the Monitor. He controls the Anti-matter of the Universe by destroying realities and positive matter of multiverse. As per the comics, several superheroes had to sacrifice themselves in order to stop him from becoming more powerful and destroying multiple universes.
The Arrowverse crossover will also feature Tom Welling as Clark Kent, Erica Durance as Lois Lane from Smallville, Kevin Conroy as Bruce Wayne, Ashley Scott as The Huntress, and John Wesley Shipp as the Flash of Earth-90.
"Arrow" season 8 episode 8 "Crisis on Infinite Earths: Hour Four" airs Tuesday, January 14, 2020 on The CW.