Epic fantasy doesn't just mean fantasy that is really good in slightly outdated slang. An epic fantasy is massive in scale with a world-shattering event or conflict. Note: we didn't say ''earth-shattering" there, because it's not usually set in the real world. Mostly it's in a fictional setting, presumably to make it easier to put in that world-shattering event.
It's exciting stuff, which is why some of the most famous book series belong in the epic fantasy sub genre. Think Game of Thrones, Lord of the Rings, and the Wheel of Time. And probably other titles without ‘of’ in there.