Erfaug

Erfaug was a malevolent demon troll that worked for Sauron. He was a Maia who took the form of a hideous acid spitting troll. 

Boromir: "Is it not a strange fate that we should suffer so much fear and doubt for so small a thing? So small a thing!" - J. R. R. Tolkien, The Fellowship of the Ring II:10

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