Here are a few of my favourite Metal Epics.
Here's a great Folk Metal epic, from my favourite Folk/Viking Metal band.
Månegarm-Hemfärd - YouTube
Here's one of my favourite Power Metal epics, from my favourite Power Metal band.
Blind Guardian - And Then There Was Silence - YouTube
and here's a Black/Folk Metal epic from my favourite Canadian Metal band. (The uploading is poor quality, the production is better on the actual album.)
Catuvolcus - Litaviccos - YouTube