Rage Of The Norsemen
The end of the world signified by Loki leading the giants against the Gods, preceded by a great winter (fimbulvetr) lasting three years with no summers. There will be constant war in Midgard; earthquakes and freezing cold will kill off mankind. The skies will darken and the final battle ends in the death of all things, Gods and Men alike.
A sure sign of Ragnarok is the third-age or wolf-age where brother fights brother. The first-age was the axe-age, the second, the sword-age.