WARNING: This article contains SPOILERS for DC's Legends of Tomorrow Season 5, Episode 15, "Swan Thong."
Legends of Tomorrow aired its season finale, and true to the show's form, it ended on a cliffhanger that sets up the next season. This finale saw Captain of the Waverider, Sara Lance (Caity Lotz) abducted by aliens. So, with the former assassin missing, there is only one person who could help the Legends bring her back: her former flame, Nyssa al Ghul (Katrina Law).
The identity of Sara's abductors is still a mystery as she was beamed up into a ship without any of the Legends noticing. With that in mind, the Legends will need expert help with tracking someone who could have been taken virtually anywhere, and the person in the Arrowverse with the most experience tracking Sara is the daughter of the Demon.
Nyssa has proven to be a fearless warrior on Arrow from the first time she appeared. The al Ghuls have also shown themselves to be knowledgable about all things in the universe, even having some knowledge about Mar Novu/The Monitor. Nyssa may be able to provide information about the alien race that kidnapped Sara or at least have a way to track them. While the Waverider still has the artificial intelligence Gideon, she can only help in issues relating to time and will not be much help when it comes to space.
Though, having Nyssa on the Waverider would create a clash with co-captain Ava Sharpe (Jes Macallan) who has shown her jealous side from time to time. When John Constantine boarded the ship and it became clear that he and Sara had a fling, Ava took issue with him. Hopefully, Ava can put her feelings aside and ask for Nyssa's help as the team would need as much help as they can with getting their captain back.
While it would be fun to see how Law interacts with everyone on the Waverider, it's up for debate whether she should stay on the Waverider as a new member of the Legends or just appear to help save Sara and then continue to hide in the shadows. Her storyline was left open after the events of Arrow and with the timeline change placed after "Crisis," she doesn't need to return to the modern-day to teach a hidden Mia Smoak how to fight as she did in the old Multiverse.
As it stands today, it's still unclear when the Arrowverse shows will be able to begin filming. If there's any silver lining in this situation, though, it's that the creative team behind Legends has ample opportunity to find ways to bring Nyssa or other Arrowverse characters into what promises to be another wild season.
Returning to The CW in 2021, DC's Legends of Tomorrow stars Caity Lotz, Dominic Purcell, Nick Zano, Maisie Richardson-Sellers, Tala Ashe, Matt Ryan and Jes Macallan.