In Norse Mythology, Ragnarok is series of apocalyptic events that will define the end of the worlds. Where giants of frost and fire will together fight the gods in a final battle that will ultimately destroy the planets.
The series of apocalyptic events is a long winter that is called Fimdulvetr that will last for a year.
A red rooster will tell the giants that Ragnarok has started, a second rooster will tell the dead that Ragnarok has started. There is another rooster will warn the gods of Ragnarok.
The god Heimdallr will play his trumpet that will bring the dead back to life, as well as the gods Balder and Hod to fight in the final battle. The world serpent will rip the sea and join the fight.
Loki and his horde will battle the Aesir on a ship made of dead mans nails. All monsters and giants will create a powerful army against the gods. The result of the war will lead to Thor and Odin and most of the gods dying.