[Huinesoron]

So I think Marec's ultimate source is MERP: Gorgoroth. The name appears three times in there, as a name for Sauron - but specifically a 'Donaen' name for him. The 'Donaen' are described as living in the foothills of the Ash Mountains (I think), and, well:

Originally Posted by MERP: Gorgoroth

Many native human tribes live in the hills. They belong to a
people known as the Donaen, a minor ethnic group in the huge Gondorian empire, descendants of the Daen Coentis that migrated westwards a long time ago.

Just how far Iron Crown varied from Tolkien's works can be seen in this quote, from a character of the Donaen:

Originally Posted by MERP: Gorgoroth

Effem dislikes the Gondorians whom he sees as foreign invaders that have come to seize the land and westernize its inhabitants. He is not particularily religious, but knows Durnu (Do. "Dark Mother"), the true ruler of his people, is more than just an abstract concept. The Dark Mother's herald, Marec, makes his home in Mordor, and the Donaen have been living on his grace since early in the Second Age. Thus, Effem supports the traditional religion, even though he tries to minimize sacrifices, since he sees them as a waste of resources.

There might be a Tolkien source for the name 'Marec', but I'm inclined to doubt it.

... that said, I've used multiple names from the apocrypha in puzzles before now, so this isn't a complaint.

hS