Now that the Earth Prime.
On Legends of Tomorrow, Crisis "Part 5" saw the superheroes finally defeat the Anti-Monitor (LaMonica Garrett) once and for all, thanks to Ray Palmer (Brandon Routh) and Ryan Choi (Osric Chau), who had the ingenious plan to shrink the cosmic despot into the "atom-verse" (not to be confused with Marvel's "microverse"). The Legends played a crucial role during the Crisis: Sara Lance (Caity Lotz), the team's captain, was revealed as the Paragon of Destiny, one of the John Constantine (Matt Ryan) was pivotal in helping locate Oliver Queen's soul in Purgatory so he could be reincarnated as the Spectre and defeat the Anti-Monitor at the dawn of time.
With the dust settling on the Crisis, end of Legends season 4, Sara Lance and her crew defeated the demons Neron and Tabitha (Jane Carr) at Heyworld, a theme park full of magical creatures, with the power of positivity (and the help of a dragon named Wickstable). After years lurking on the outskirts of the Arrowverse, repairing problems with the timeline (that they often caused themselves), the Legends begin season 5 more famous than ever as they finally get the recognition that has been denied to them. But their win against Neron came at a cost; the timeline was altered so that Zari Tomaz (Tala Ashe) never became a Legend and instead, her place on the team was filled by her brother Behrad (Shayan Sobhian), who is now alive. Worse, the Legends are unaware of the magical switch.
However, Sara Lance will be irrevocably changed after the events of Crisis. Losing Oliver meant that everyone she considered her family is now dead (although it's not yet clear which version of her sister Laurel is now living on Earth Prime). But during Crisis Part 5, Sara also took command of the superheroes, first when they faced a giant Beebo — an illusion by Sargon the Sorcerer (Raul Herrera) — and later against the Anti-Monitor. Arrowverse's version of the Justice League alongside Flash, Supergirl, Superman (Tyler Hoechlin), Black Lightning (Cress Williams), J'onn J'onzz (David Harewood), and Batwoman (Ruby Rose). Still, Sara will be nursing the emotional scars from Crisis for a while, which is bound to affect her relationship with Ava and her leadership of the Legends.
Ray Palmer's future also bears watching since it's already known that Brandon Routh and Courtney Ford, who plays Nora Darhk, will, unfortunately, leave Legends of Tomorrow at some point in season 5. During Crisis, Ray met his doppelganger, who happened to be Kingdom Come Superman, but the Atom was a pivotal reason why the heroes saved the Multiverse. The events of Crisis could be a catalyst to why Ray and Nora will ultimately exit the Waverider.
The Legends will spend season 5 chasing "Encores", history's greatest villains released from Hell by Astra Logue (Olivia Swann), but now that Earth Prime exists, it means the Legends may encounter history that has been changed due to the merging of Earth-1 with Earth-38 and Black Lightning's Earth. So while Legends of Tomorrow will lean heavily into their trademark weirdness and humor, whatever alterations to history the Legends discover in Earth Prime's timeline certainly bears watching.