Ragnarök: The final battle and accompanying calamities

Odin is supposed to lead the gods during the battle, while Loki is expected to lead the monsters, the fire giants, and the Jötnar. 

Ragnarök is often described as the final battle, as the majority of the Norse gods, giants, and monsters are expected to perish during the clash. Along with them, virtually everything else in existence will be annihilated.

Among others, Thor, Odin, Heimdallr, and Loki are foretold to die during Ragnarök. Apart from the battle, a number of calamities are also expected to occur, including natural disasters and the world being drowned by water.

After the end of the aforementioned disastrous events, the world is supposed to go through a period of restoration, emerging from the clashes reinvigorated and fertile. 

The gods who lived through Ragnarök and returning gods are expected to meet, and the world is set to be repopulated again by two survivors of the human race, Líf and Lífþrasir.   

Literary sources

Ragnarök is thoroughly described only in the Völuspá, an Icelandic poem (Sibyl's Prophecy), and in Prose Edda (also known as the Younger Edda or Snorri's Edda) of Snorri Sturluson.

Experts believe that the Icelandic poem dates back to the 10th century, while the Prose Edda dates to 1241. Furthermore, the Prose Edda mostly follows the Völuspá.

Both sources claim that Ragnarök would be preceded by cruel and unforgiving winters and moral disarray. After that, the monsters would attack the gods from all sides, while the gods would offer resistance, and many among them would die heroic deaths.

The sources provide some detail on the nature of the natural disasters that are expected to occur during Ragnarök - the sun would turn dark, the stars vanish, and the earth would sink into the sea.

After the epic clash of the two forces, the earth would remerge, and the surviving gods would reunite.