This is where Yuna, Skyla, and Nightstar find the Dragon's den in The Alliance of Berk and Equestria.
Skyla: So, what now? Yuna, your test is tomorrow. You know you're going to have to kill a... [Whispers to Yuna so Nightstar doesn't hear] kill a Monstrous Nightmare.
Yuna: I know. Don't remind me.
[then Nightstar's ears lift up as she hears something and then she changes direction]
Yuna and Skyla: Whoa!
Yuna: What is it, girl? What's going on?
[then a Monstrous Nightmare appears]
Yuna: Get down!
[then soon they are amongst a whole herd of dragons]
Skyla: What's going on?
Yuna: I don't know. Nightstar. You've got to get us out of here, girl.
[but Nightstar shrugs it off and continues flying with the other dragons, and then Skyla sees a Star Shadow carrying a huge fish]
Yuna: It looks like they're hauling in their kill.
Skyla: Uh, what does that make us?
[A Hideous Zippleback looks at them but continues on]
[then all the dragon start flying through rock formations and then they come to a huge volcano]
Yuna and Skyla: Whoa!
[inside, is the dragon's den!]
Yuna: What Aunt Celestia and Mama wouldn't give to find this.
[Nightstar then lands and hides behind a rock tower and they watch]
[all the dragon drop their loads into a huge hole]
Yuna: [Sarcastically] It's satisfying to know that everything they steal has been dumped down a hole.
Skyla: They're not eating any of it.
[then one Crystal Dragon drops only a salmon, and then there is a loud roar as the dragon tries to get away a huge Dragon head appears and eats the dragon!]
Skyla: [gasps] WHAT IN THE NAME OF EQUESTRIA IS THAT?!
Yuna: I have no idea!
[then the dragon sniffs around]
Yuna: Alright, girl, we gotta get out of here. Now!
[they and all the other dragons fly out as the huge dragon foolows and then it grabs a Windscraper and eats it]
[they 3 arrive back at the cove]
Skyla: No, it totally makes sense. It's like a giant beehive. They're the workers, and that's their queen. It controls them. [hops off Nifghtstar after she lands] Let's tell daddy.
Yuna: No, no, no! [Grabs Skyla] We can't tell your dad, if we do, they'll kill Nightstar! We need to think things through first!
Skyla: Yuna, we just discovered the Dragons' Den. The thing Aunt Celestia and Luna been after for a long time. And you want to keep it a secret?! To protect your pet dragon?! Are you serious?!
Yuna: Yes, I do.
Skyla: Okay. Then what do we do?
Yuna: Just give me until tomorrow. I'll figure something out.
Skyla: Okay. I'll meet you back at the castle. [races off]
[Nightstar then looks at Yuna]
Yuna: What are you looking at?
Yuna: Alright then. [walks off] She you tomorrow girl, [under her breath] I hope.