An epic "is a long verse narrative on a serious subject, told in a formal and elevated style, and centered on a heroic or quasi-divine figure on whose actions depends the fate of a tribe, a nation, or (in the instance of John Milton's Paradise Lost) the human race." (Abrams, Glossary of Literary Terms, 7th ed., p.76)

*The hero is a of great national or even cosmic importance.

*The setting is ample in scale, and may be worldwide, or even larger. 

*The plot entails superhuman deeds in battle,

*typically written in a grand, idealized style.