This is it, the end of the worlds as we know them. Despite all of Odin’s efforts (and there are more covered in some of the heroic sagas), Ragnarok will arrive. Loki, of course, is the primary mover and shaker, here, who breaks free from his bonds, causing earthquakes and other destruction. Next comes Fenrir, with more of the same. All of this destruction isn’t just in Asgard, but throughout all of the nine worlds, particularly Midgard, AKA Earth.
Loki’s prison break is the first blow against humanity. Thanks a lot, Loki. The armies from Muspellheim that Loki leads will begin throwing fire at the Aesir, which causes more death.
What follows is a series of duels. Fenrir vs Odin, which Odin loses, but his son Vidar avenges him by ripping Fenrir’s head apart, then stabs him. Thor confronts the world serpent, Jormungand. He kills the monster, but it poisons him, killing him after nine steps. Heimdall and Loki kill one another. The hound Garm from the underworld fights Tyr; they both die. Freyja attempts to kill Surtur, but fails without his sword. Surtur now sets fire to, well, everything. This is the final destruction of Ragnarok.
So, these duels are remarkable. Armies are clashing, but the gods pair off. This is likely part of the warrior code from the Norse where they would not intrude on another’s single combat. Given that these stories were handed down from a Medieval world, this makes a degree of sense. The Norse stories are set in the same time period that gave rise to King Arthur and his knights, so the elements of the chivalric code are not surprising.
However, this is the very cause of their defeat. They do not act as an army, but as single opponents. Their respective armies clash as armies, but the single combat of the gods is to treat this as something other than the war that it is. Had they acted in concert on the battlefield, lending support to one another, things might have gone very differently.
But, like with Fenrir, we have to realize that the gods are bound by the strictures of fate. These matchups are as destined as Wrestlemania, and the outcome as predictable. This is a powerful message by the culture, that not even the gods can escape fate, and that they are not truly eternal. It’s also the way to wipe the slate clean. The duels are almost tailor-made to be mutually destructive; only a couple of exceptions stand out as true victors.
There are survivors, sure, but not very many. Two sons of Odin and two sons of Thor. Baldur and his killer Hodur both return from the dead. Two humans somehow survive Surtur’s flames, and kickstart the rebirth of the post-Ragnarok world. So even with the vast destruction of the worlds, humanity, and the gods, the Norse recognize that there will be something that comes after, and a rebirth of sorts. No other apocalypse myth comes close to the level of destruction inherent in the Norse myth, but still there is rebirth.