What do people know about the Mythos? Part 3

Part 1 , Part 2 Last installment for a while, since as you'll see shortly I am really stretching what qualifies as the Mythos. But I suppose that is part of the point. Anyway, fun series, definitely will return to the format in the future (probably for public domain goodie roundups). Nodens 1) An obscure Celtic god, about whom next to nothing is known besides associations with healing, dogs, and…