General:
* Grand: suggests magnificence and impressive scale.
* Monumental: emphasizes the enduring significance or lasting impact.
* Heroic: highlights the bravery and deeds of the protagonists.
* Legendary: implies a story passed down through generations and steeped in folklore.
* Extraordinary: emphasizes the exceptional nature of the event or story.
* Remarkable: suggests something worthy of notice or attention.
* Vast: focuses on the immense scope or size of the event or story.
* Magnificent: emphasizes the splendor and grandeur.
* Impressive: suggests a strong emotional impact.
More specific:
* Prodigious: suggests something of extraordinary size or extent.
* Colossal: emphasizes immense size or power.
* Mythical: suggests a story originating in legend or folklore.
* Legendary: implies a story passed down through generations and steeped in folklore.
* Historical: emphasizes the historical significance of the event or story.
* Grandiose: suggests a sense of ostentation or exaggerated importance.
In relation to a narrative:
* Masterpiece: implies a work of exceptional quality and skill.
* Masterful: suggests a high level of craftsmanship and artistry.
* Compelling: suggests a story that holds the reader's attention.
* Engrossing: implies a story that completely absorbs the reader.
The best synonym for "epic" will depend on the specific context and the nuance you want to convey.