This is how the dragon arena and Nightstar to the rescue goes in The Alliance of Berk and Equestria.
Crowd: Yuna! Yuna! Yuna! Yuna!
[then Princess Celestia and Princess Luna step forward]
Princess Celestia: Settle down!
Princess Luna: Good citizens, if someone had told me that in a short time, Yuna would place in frst in the dragon training, I would've had her lead her own Dragon fighting army a long time ago! But here we are. And no one's more surprised or proud than me. My filly becomes a dragon slayer!
Skyla: Be careful with that dragon.
Yuna: It's not the dragon I'm worried about.
Skyla: What are you gonna do?
Yuna:Put an end to this.
Skyla: [She eyes her, dubious.]
Yuna: I have to try. Skyla, if something goes wrong... just make sure they don't find Nightstar.
Skyla: I will. Just... promise me it won't go wrong.
Comet Hoof: Alright, Yuna, go and knock em' dead!
Yuna: [gulps] [she then enters the arena as the gates are closed]
Button Mash: Show 'em how it's done, Yuna!
Yuna: [grabs a sheild from the weapon rack and then a small dagger]
Princess Luna: Hmmm, I would've gone for the sword.
Yuna: [sighs] I'm ready.
[they then raise the gate for Monstrous Nightmare's pen and then it bursts out (covered in flames)]
[it then climbs around the arena and then fires a blast of fire out the cage and then it notices Yuna and slowly approaches her]
Pepper Clark: Go on, Yuna let em' have it!
Yuna: [drops her sheild and the dagger]
Princess Luna: What is she doing?
Yuna: It's alright. It's alright. I'm not gonna hurt you. I'm not like the others.
[the dragon then looks to the crowd and then back at Yuna]
Princess Luna: Stop the fight.
Yuna: No! I need you all to see this. [put her hoof out for the dragon to smell] They aren't what we think they are. We don't need to kill them.
[the crowd watches in awe and shock]
Princess Luna: [in Royal Canterlot voice] I SAID, STOP THE FIGHT!!!
[but the echo of her voice makes the Monstrous Nightmare revert back into its regular state. And then it chomps its teeth at Yuna]
Yuna: YAH!! [she starts running and then avoids a fire blast from the dragon] AAAAAAAAAAAAAHHHHH!!!!!
[inside the cove, Nightstar hears Yuna's cries of fear]
Princess Luna: Move aside! [she start to head for the gates]
Skyla: Yuna! [she then grabs an ax and pray open the gate for her to squeeze under it]
Nyx: Hang on, there! [she jumps through the bars]
[back the cove, Nightstar is struggling to climb out and then she makes it to the top]
[Yuna continue to run form the dragon and tries to grab a sheild but the dragon prevents her]
[Nightstar is now racing through the forest]
Nightstar: [growling and panting as she races on]
Princess Luna: [gets the gate open and races for the arena's gates]
Cadance: [races to the arena gates too]
Skyla: Yuna! [she then picks up a club and throws it at the dragon which chases her next]
Nyx: Hey, big boy! Come and get me! [throws a rock at it]
[then it starts chasing Nyx]
Princess Luna: [opens the arena gates] Come on, this way!
[the 3 run for the gate, Skyla runs into and Cadnace grabs her as Luna then grabs Nyx, and she reaches out fo Yuna but the dragon fires a blast of fire in front of her, blocking her and then it swats Yuna and pins her down his its claw]
Edd: Not good! Not Good!
[then a shrill growling is heard]
Nightstar: [races into the scene, and then roars as she fires a plasma blast at the cage, blowing a hole in and then she flies into the arena]
[Nightstar then starts to attack the Monstrous Nightmare]
Princees Sharon: A Night Fury!
[Nightstar and the Monstrous Nightmare fight]
[But Nightstar overpowers the Monstrous Nightmare and throws it off herself.]
[the Monstrous Nightmare then turns and goes back to its pen]
Yuna: [pushes on Nightstar's sount] Nightstar, go. Get out of here!
[then several of the citizens to race into the arena]
Princess Luna: [grabs her shotgun]
Skyla: Aunt Luna, no!
Yuna: No, Mama, she won't hurt you!
[Nightstar then sees Luna and then snarls]
Yuna: No, don't! You're only making it worse!
[Nightstar then throws aside some of the other equiens and then tackles Luna]
Yuna: Nightstar, STOP!!
Nightstar: [prepares to blast Luna with a plasma blast]
Yuna: No! No! NOOOOO!!!
[Nightstar then stops and looks to Yuna]
Rainbow: Get it!
[The others then start to overpower Nightstar and then they start to pin her down.]
Yuna: No! Please, jus-- [Skyla holds her back] just don't hurt her! Please don't hurt her.
[Nightstar is getting scared as she's pinned]
Yuna: No, please!
Princess Luna: [looks at Nightstar and then Yuna] Keep that Night Fury there. First I have something to do with my daughter.
[Luna then brings Yuan into the throne room]
Princess Luna: Yuna, I am very disappointed in you, young lady!
Yuna: Mama, I...
Princess Luna: How could you possible keep this kind of thing a secret from me?! I thought I taught you better! You lied!
Yuna: I know, but... Ugh, it's all so messed up!
Princess Luna: So everything the other day, a trick!?
Yuna: I should have told you before now. Take this out on me, be mad at me, but please... just don't hurt Nightstar.
Princess Luna: That Night Fury? That's how your worried about? And not all of those equines that were almost killed?!
Yuna: She wasn't trying to kill them, she was just protecting me! She's not dangerous!
Princess Luna: Yuna, those beasts killed THOUSANDS OF OUR KIND!!!
Yuna: AND WE'VE KILLED MILLIONS OF THEM!!! They defend themselves, that's all! They raid us because they have to! If they don't bring enough food back, they'll be eaten themselves. There's something else in their den, it's a dragon like--
Princess Luna: Their den? You've been to their den?
Yuna: Uh, did I say, "Den?"
Princess Luna: How did you find it?!
Yuna: No I didn't find it, Nightstar did. Only a dragon can find it.
Princess Luna: [looks shocked at first but then grins]
Yuna: Oh, no, no. Mama, no! Mama! It's not what you think! You don't know what you're up against! It's like nothing you've ever seen! Mama, please! I promise you that you can't win this one! This isn't like fighting our other enemies, this battle can 't be w...
Princess Luna: You've thrown your lot in with them. You're not a Princess. You're not my daughter. [to a nearby royal guard] Tell Tia to ready the ship! [leaves]
Yuna: [sadly looks at the door]
[Before walking to the docks, Luna staggers back, realizing the mistake she just made.]
["Padme's Destiny/Birth of the Twins" starts playing]
Princess Luna: [panting]
Princess Celestia: Come on, Luna! PUSH!!
Princess Luna: GAAAAAAAHHHH!!!!! AAAAAAAAAHHHH!!!!
Nurse: It's a baby girl.
Princess Luna: Yuna.
Princess Celestia: Yuna?
Princess Luna: That's what I wanna call her.
Hiro: I like that name, "Yuna".
Princess Luna: Let me see my baby.
Nurse: [hands her over]
Yuna: [still crying]
Princess Luna: Yuna, my daughter.
Yuna: [calms down and falls asleep by nuzzling Luna's chest]