Battles Lost and Won

"Battles Lost and Won" is the twenty-third episode and season finale of the third season of The CW series Supergirl, and the series' 65th episode overall. The episode was written by Robert Rovner & Jessica Queller and directed by Jesse Warn. It first aired on The CW on June 18, 2018.

This marks the final regular appearances of Jeremy Jordan as Winslow "Winn" Schott, Jr., Chris Wood as Mon-El and Odette Annable as Samantha Arias/Reign.

The episode received positive reviews from critics.

Plot
As the earthquakes worsen, Supergirl, Alura, Guardian, and the DEO protect National City; Imra and Brainiac 5 return to help. M'yrnn gives J'onn one final memory before merging with the earth to stop the terraforming and the heroes defeat the priestesses. Sam finds the fountain in Juru and makes peace with her mother. She drinks from the fountain and defeats Reign using the sword. However, this leads to Sam, Mon-El, and Alura dying, so Supergirl goes back in time and changes the outcome of their fight using the Harun-El. Brainiac 5 decides to stay on present-day Earth because a distant relative (who did not die in the Blight) has started wiping out all other AI and asks Winn to take his place with the Legion. Winn accepts his offer and travels to the future with Mon-El. J'onn steps down from the DEO and promotes Alex as director. Kara decides to stay on Earth instead of returning to Argo with her mother. Sam, completely rid of her Kryptonian side, returns to her life with Ruby. Lena gives Alura all of the Harun-El and a mathematical formula to create more, but synthesizes a portion for secret experiments.

A duplicate Kara appears in Siberia at the same time Reign is defeated with the Harun-El.

Production
Filming took place in Vancouver and ended on April 28, 2018.

Ratings
The episode was watched live by 1.78 million viewers, and had a ratings share of 0.5/2, during its original broadcast. A decrease of 0.34 million viewers compared to the previous season finale, and 0.02 million more viewers compared to the previous episode.

The episode attracted 590,000 viewers upon its British premiere, making it the 2nd most watched programme on Sky One for the week.

Critical response
The review aggregator website Rotten Tomatoes reported an 80% approval rating for the episode, based on 10 reviews, with an average rating of 6.68/10.

Jesse Schedeen of IGN rated the episode 7.1, complementing the "great, emotionally charged scenes and a generally strong emphasis on Kara and her supporting cast" but criticising the episode's inability to wrap up the Reign storyline.

Delia Harrington of Den of Geek gave the episode 2 out of 5 stars, noting that "it seems the writers chose to use the season finale to clear out some of the troubling elements of the season and do their best to set up more interesting stories next season".