So Ryver Nymph was spelled that way on purpose. Mostly just because I though it was interesting for both words to use a "y". Though I do like the idea that it was the name of the place they were discovered.
So with the silver dust. If you fail the save you gain the arousal based effects. Then with the d4 if you roll a 1 you are also "high" like you would be on other drugs. Similar to weed or mushrooms.