"Supergirl" is about to learn that Hell hath no fury like a Queen of Daxam scorned. After Rhea ventured across the galaxy to reunite with her son Mon-El and bring him home, he chose to stay with Kara over his own family. Mon-El’s father, Lar Gand supported his son's decision, a siding which ultimately led to Rhea killing him. A vengeful Rhea has now set her sights on Kara, Mon-El and Earth, and woe be to whomever stands in her way.

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“Supergirl” EP Andrew Kreisberg recently spoke with CBR about Rhea’s endgame, Supergirl’s moral dilemma, the return of Tyler Hoechlin's Superman to the show, and the arrival of Mark Gibbons as General Zod.

CBR: Lena has always struggled with being a Luthor. How will Jack’s death impact her?

Andrew Kreisberg: Lena has lost a lot in her life. It’s always interesting to me that the heroes and villains of comic book stories tend to have the same backstory. They just go in a different direction. You look at Kara and everything that she’s lost -- she lost her birth planet, her birth parents and world. She lost her adopted father. And yet that brought her closer to the people that she loves and helped mold her into the hero she is. Then you look at Lena, who has lost her father, she’s lost her brother. Now, she’s lost Jake. Even Lena said that she starts to worry about what’s going to happen to her when she loses too much.

She’s actually in a very vulnerable place right now, which makes her perfect prey for Rhea, who is going to come in and become a bit of a mother figure for her. At this time, that’s the very thing Lena wants with her own mom. We’ve been building up to this emotional place for the two of them.

In her anger, Rhea killed her husband and stated she is not finished with Earth. What is her endgame? At this point, is it all about her son, Mon-El?

I don’t want to give too much away because it’s part of the surprise coming in the next few episodes. Her plans definitely include Kara, Mon-El and Lena. She has a master plan. She’s very bright, very dangerous and she’s very ruthless. Rhea is used to getting what she wants. She’s going to set the table for the last few episodes to enact her master plan. What exactly she wants from all those people – you have to tune in to find out.

Kara must team up with Maggie to save Alex from a "Saw"-like trap in tonight’s episode. What does that allow you to explore in terms of these relationships?

We’ve always wanted to do a Kara/Maggie episode. When we were sitting down to think of it, we realized that the thing they obviously had in common is they both love Alex. We thought it was an interesting dynamic. It started from a place of, “Who gets to make the decisions about someone? Is it their family, or is it their girlfriend/boyfriend or husband? Who has a bigger say?” We also really liked the different perspective of what a cop would think of a superhero. We’ve always been a fan of “Gotham Central” and that ground’s-eye point of view of what superheroes do for a living. The more we talked about it, the story started to form. What does Maggie do to stop crime versus what does Kara do to stop crime? Throw Alex’s kidnapping into the mix and then they see very different ways with which they attack it even though they are both doing whatever they are doing because they love Alex and they want to get her back. It was a great way to deepen the bond between Maggie and Kara. For us, it’s a little bit of a departure episode. There are very little visual effects in it. It’s this great moral dilemma. As you watch the episode, what is Kara willing to do to get Alex back?

Mon-El isn’t the same guy as he was at the beginning of the season. How comfortable is he in his own skin now, and what is his arc in the next block of episodes?

Mon-El is very comfortable. He’s grown into himself and is in love with Kara. He’s the best version of himself. For all of Mon-El’s selfishness, he was never quite comfortable being this Prince of Daxam. Being on Earth, and being with Kara, has really allowed him to become the person that he wants to be. They are going to be put to the test in these last episodes when they are faced with some unimaginable choices. Each of them has to evaluate what it means to be a hero. And, can their idealisms survive what they are up against? Is winning more important than values? They are all put in these great moral dilemmas and have to make these choices. Is it love or duty? These are some of the biggest episodes we’ve ever done in terms of scope, visual effects and stunts, but they also have some of our best emotional material. Hopefully, the audience thinks so, but we really bring everything that’s happened this season together in these last few episodes.

What is “Supergirl’s” version of General Zod, and what brings him to Earth?

I don’t really want to say too much about Zod. How and why it happens is a fun surprise. As far as his costume is concerned, we took a page out of the older, Nazi uniform that he used to wear, which was very cool. That name instantly means something to fans of Superman and Supergirl. It’s a bit of a cameo surprise in the episode.

Superman returns for the finale. How crucial is he in the upcoming battle?

He’s incredibly crucial. I love Tyler in the part -- he’s so good. It’s a bit of a different interpretation of Superman than you’ve seen. In our show, Superman has been [a superhero] for a decade, and he’s pretty comfortable with being Superman. A lot of interpretations are of him getting his start, at the beginning. For us, he’s so comfortable in the role, but the show is called "Supergirl," so our Superman is here in service of Supergirl. He’s her family. He’s her conscience. He’s her mentor.

There’s also some very cool scenes between the two of them. As for wanting him to come back, we would have him back all the time, but the show is called “Supergirl.” You really want it to be about her. Our partners at DC and Warner Brothers have been very generous to us, letting us have that character appear on our show. We’re grateful for every opportunity we get.

What else can you tease about the finale and what it sets up for season three?

We have amazing guest stars in the finale. We are bringing back people we’ve had all season. We have Calista Flockhart coming back. In the last two episodes, we have Lynda Carter returning as the President, Sharon Leal is coming back as M’gann. Obviously, there’s Tyler as Superman. These are some of the biggest episodes we’ve ever done. We’re so proud of Teri Hatcher, and so amazed she’s on our show and killing it as Rhea. There is a feature film quality finale, with huge guest stars, stunts and visual effects. We will get a glimpse of the Season 3 villain in the finale, which we’re also excited about.