Ragnarök

Ragnarok refers to the legendary event which is due to happen in Norse Mythology. The term "Raganrok" literally means Doom of the Gods, as Gods it refers to the Norse Gods such as Thor, Odin, or Loki.

Brief Description of the Event
It is said at the very start of the Ragnarok the Gjallarhorn of Heimall, the guardian of the Bridge Bifrost (the bridge connecting Asgard, the realm of Gods and Midgard, the world) have been sound. At this event the gods fight against the fire Jötunn with Surtr leading them. Despite Loki being a Jötunn as well as a god, he still stood at the side of the gods in this battle.

Proper Desciprtion
It is said at the very start of the Ragnarok the Gjallarhorn of Heimall, the guardian of the Bridge Bifrost (the bridge connecting Asgard, the realm of Gods and Midgard, the world) have been sound. This indicated that Ragnarok has begune. Just then the sun's rays darkened until it was pitch black, like in the night. From the south the ones that oppose the gods, the Eldjötnars (litterally meaing fire giants in Norse), who is leaded by their leader Surtr. After a great battle in which many gods and even more Eldjötnars are killed. Surtr, the black one, releases a fire which annihilates the whole original world, leaving only 2 humans ( Líf and Lífthrasir) ,who hid in the woods Hoddmímis holt, behind.

Acknowledgements
http://en.wikipedia.org/wiki/Ragnar%C3%B6k