A few videos to summarize the events
The Beginning of the End
Although there is no exact order to the beginning of the end events, 3 important things will occur. There will be a 3 year winter: Fimbulvetr, with no springs or summers, nothing will grow, and the world will be covered by darkness. There will be large scale wars amongst mortals, even families will turn on and fight against one another. Also, all signs of morality, goodness, and righteousness will disappear.
What will the Bad Guys do?
Yggdrasil will be shaken from it's roots to it's top, resulting in massive earthquakes in Midgard. The shaking of the World Tree will sever the bonds of Loki and Fenrir, who will be released to begin the final battle.
The sea will overflow and great tidal waves will flood the land as Jormungander moves towards land. It will also use it's venomous breath to poison both the land and air.
Jormungander's swimming will raise the ship Nagflar and many giants will set sail for the final battle. It is a ship comprised of the dead's finger and toe nails, as well as other body parts. Another ship will set sail from Hel with Loki as it's captain. It will carry the dead who were offered freedom from Hel in exchange for fighting for Loki.
What will the Good Guys do?
Heimdall will sound his great horn to announce the end of time. Valhalla will be opened and all Gods of Asgard, the Heroes of Valhalla, dwarves, elves, and other beings of good will proceed to the final battle
The Final Battle
This great void will not be the end. Eventually, the Earth will rise once again from the sea, a more lush and fertile place than ever before. Baldur will return from the Underworld to usher in this new age as the head deity. Two humans, Lif and Lifthrasir will somehow survive the fires and will repopulate the Earth. Some gods will be reborn and men and gods will walk together in harmony. All evil is not vanquished however, the Nidhogg serpent still gnaws at the roots of Yddrasil....
A dramatization, but potentially how the story might have been first shared in Viking times