Hark! Are those the first harbingers of Chapter Three I spy on the horizon?

[Shepherd]

I don't recall such a thing from the listing of his arsenal, but does Doug have a song that'll allow him to impose silence on one specific person

There is a slim chance that Simon & Garfunkel's Sound of Silence may do that, although I think it is far more likely to drop Doug into a deeply symbolic precognitive trance which he'd have to laboriously analyze in order to learn anything useful. Of course, it may be funny to do this and then try to discern the vision's meaning with Professor Trelawny's help.
edit: I idly wonder what would happen if Doug combined this with I'll Play for You and targeted Trelawney.
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"Anyone can be a winner if their definition of victory is flexible enough." - The DM of the Rings XXXV