That is a motif and the theme of the story. But it's also going to be a physical plot device. Is it a place, an object, a non-existent myth? Who knows?
Epic is when a bunch of awesome things collide in an explosion of crazy awesomeness. People die, people live, people fall in and out love, countries collapse, countries rise, and most importantly, people fight in over the top action with the outcome deciding everything! Epic is when the only word you could possibly think of to describe something like that is EPIC!!