Before the Legends of Tomorrow can welcome John Constantine into their ranks, they will have to deal with the threat of Mallus in the third season finale. And with only so many seats on the Waverider, don't be surprised if another team member makes an exit.

Showrunner Phil Klemmer spoke about the cast growing for Season 4, teasing that the Legends would have to say goodbye to one of their allies in Monday's finale.

"It does [pave the way for an exit], it does," Klemmer said to TVLine. "There’s heartbreak in the finale. A Legend leaves."

Klemmer spoke about the possibility of Nate Heywood and Amaya Jiwe's romance coming to an end, which could lead to one of them leaving the show. "As far as [Amaya] and Nate, I don’t know if love is made to last in the world of the Legends."

The latest season began with the two broken up and Amaya remaining in her own time in the past, and has constantly referenced her need to return in order to start a family that would eventually lead to the births of Kuasa and Mari, with the latter inheriting the Spirit Totem. Of course, these events mean she would have to leave Nate.

In the penultimate episode, Amaya returned to her village in order to prevent its destruction, and in doing so it caused the anachronism that freed Mallus from his prison. She also learned that her memory of Nate had been wiped away, possibly due to the flash gun.

But while someone might be leaving the team in the finale, the episode will also bring back a former member of the team. Franz Drameh returns in this episode to reprise his role as Jax, the still-living half of Firestorm.

"The Jax we meet in the finale isn’t the same one who left our team a matter of months ago — he has been inspired by what he learned from his friend and mentor Martin Stein," Klemmer said. "Being a time traveler is like living in Neverland, where you never have to grow up, and having Jax return to our show after a stint in the real world is a bittersweet reminder of what his friends and former teammates are missing.

"When we started this show three years ago, we never would have guessed that the youngest Legend would be the first to 'grow up,' or that the guy that had to be tricked into joining the team would be the one to answer the Legends’ call in their hour of need."

Fans will get to see some familiar faces — and bid others farewell — when the season finale of Legends of Tomorrow airs on The CW.

Are you excited to see how the Legends defeat Mallus? Let us know in the comments section!