|Season 4, Episode 13 (73)|
|Laurel's Sacrifice||The Prometheus Project, Part 1|
PART 1 OF 7: THE LEADERLESS FLOCK- Thea Queen, Carrie Cutter, and Ray Palmer lay siege to the Prometheus compound to free Laurel Lance and Alexandra Danvers. Nyssa Raatko tails serial killer Lyle Corley, while Kara Danvers and Clark Kent discover Barry Allen has also been taken by the Luthors.
- Katie Cassidy as Laurel Lance/Black Canary
- Katrina Law as Nyssa Raatko
- Jessica de Gouw as Helena Bertinelli/Huntress
- Willa Holland as Thea Queen/Speedy
- Katie McGrath as Tess Luthor
- Chyler Leigh as Alexandra Danvers
- with Amy Acker as Brainiac
- with Katheryn Winnick as D.I.S.C.O.R.D.
Special Guest StarsEdit
- Michael Rosenbaum as Lex Luthor (Earth-10)
- Stephen Amell as Al Sah-him
- Grant Gustin as Barry Allen/The Flash
- David Ramsay as John Diggle
- Audrey Marie Anderson as Lyla Diggle
- Melissa Benoist as Kara Danvers/Supergirl
- Tyler Hoechlin as Clark Kent/Superman
- Callum Blue as Greg Osborne/Black Arrow
- Sofia Boutella as Mercy Graves
- Deborah Ann Woll as Andrea Beaumont/The Phantasm
- and Brandon Routh as Ray Palmer/ATOM
- Matt Letscher as Eobard Thawne
- Brenda Strong as Leticia Luthor
- Amy Gumenick as Carrie Cutter/Cupid
- and Marie Avgeropoulos as Diana, Princess of Themyscira
- Matt Barr as Lyle Corley
- Antagonists: Lex Luthor (Earth-10), Leticia Luthor, Tess Luthor, Mercy Graves, Alexandra Danvers, D.I.S.C.O.R.D., Lyle Corley
- Title meaning: Leticia's derivative name for the fledgling Justice League.
- Kara, Barry, and E3 Oliver were last seen in Save My City.
- John was last seen in Tower of Babel, Part 1.
- This episode takes place on January 19, 2020.