Hermóðr is in Midgard ,or Earth, in front of Thor's house doorstep. Thor opens the door.
"Ah Hermóðr, my mail delivery day has not happen. Why are you here?", Thor asks.
"Thor, I got a measage from the Princess of Equestria, it's urgent. She wants you to come to her castle."
Thor pats Hermóðr's head.
"Good old Hermóðr." He opens his hand to summon his hammer, the Mjölnir, as he flys to Equestria.
Meanwhile in Celestia' castle,
The Main Six, Spike, and Starlight Glimmer walk to Celestia's throne room. Celestia is stranding in one of the glass windows.
"Why did you want to see us, Celestia?", asks Twilight.
"Yeah, what's going on?", aks Rainbow Dash.
"Not yet", Celestia says, "we're waiting for someone."
"Who?", Starlight asks.
Thor walks in the room as he bows down to Celestia.
"Your highness.", Thor says as he stands up.
"No need for bowing Thor, I'm afraid I have terrible news."
"What is it Celestia?", Twilight asks.
"Has Loki planned his evil mischeifs again?", Thor asks.
"No I'm afraid it's much worse." She turns to Thor. "Have you ever heard of the Mane Six?"
"Yes, indeed I have."
Celestia nods.
"Girls", Celestia says, "this is Thor. He is the prince of Asgard and God of lighting."
"Celestia, what is Asgard? How come we never heard of it before?", Starlight asks.
"That's cause Asgard is not part of Equestria, it's part of the ten realms."
"Ten realms?", Twilight asks confused.
"Our universe has ten different worlds, including Equestria and Asgard." Celestia continues, "other realms such as Niflheim, Muspelheim, Midgard, Jotunheim, Vanaheim, Alfheim, Svartalfheim, and Helheim are inhabited by different species. All of the ten worlds are in the cosmos that are all connected by the branchces of Yggdrasil. All the worlds are so close together that by connecting them it is a shape of a tree. We called it The World Tree."
"What about the world where Sunset lives?", Twilight asks.
"That world is in another universe, the ten realms are part of our universe. I never tell anypony about this because I wanted to hide from them about the horrible truth."
"You mean?", Thor asks.
"Ragnarök", Celestia saids.
"What is Ragnarök?", asks Spike.
"Ragnarök is a propercy, a future tale waiting to be true. They say when Queen Chrysalis loses her changling army, she will somehow end Equestria and Asgard, thus killing me, Odin, Loki, Celestia, Luna, and other important gods and ponies.", Thor explains.
"But she did lose her army.", Starlight says.
"That's what I want to tell you. Me and my sister have been trying to delay this event ever since the beginning. And I forgot to mention since Twilight's the princess of Ponyville she will also die." Celestia says.
"How do we stop it?", asks Fluttershy asks.
"We can't", Thor answers," this is an event we can't get away from. We don't know when this will happen but we have to try in our power to delay it as much as we could. I'm going back to Asgard to warn everyone"
Thor flys out, crashing a window leaving Equestria.
"What about the rest of everypony?", Twilight asks.
"I'm afraid the propercy never explains in detail, I guess we will have to find out sooner or later.", Celestia answers.