I believe the martyr is entering some evil ridden dark place, where he must fight off some perverse shadowy being. If so, why isn't the land around it dark? The environment looks too "good" compared to the relatively small evil place.
Or maybe these are remains of a past time in which this land was evil, and now this hero is returning to inspect any remaining evil presence or maybe he is interested in the evil arts and is turning to shadow himself.
Interesting piece, faved it.