User blog comment:Diyartifact/Shepard's adversaries/@comment-1888392-20120410045931/@comment-2079715-20120410120558

Now that you mention facelessnes, i remembered 1 villain from Wheel of Time series of books. There were an old city in ruins there. The city was so evil that the souls of it's citizens didn't go anywhere, but stayed there and are forming a Fog each night, and the Fog devours every living being it encouters in or around the ruined city.

Now THAT's what you call a Faceless adversary. Only thing you know about it is what it is. You don't know who it is, why it is doing it, how it is doing it... nothing. But you're scared shitless of it.