I believe the Fluffy would be so scary that you might give players a heart attack
Looking at Greek mythology is a good idea, but you might want to alter the creatures a bit (Like a Minotaur with snakes and a Medusa with horns. Yeah, right).
You could also get your creatures from a book called "De Heersers der Duisternis" in Dutch. I don't know the original name (it isn't mentioned in the book, but it would most likely be something like "The rulers of Darkness"). It is written by Tanith Lee and part of it describes daemon society.
You might be able to create a quest based on them (which would be set in the equivalent of the underdark).
And the Earthsea books are written by LeGuin (which I already said before on page five)
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The last arrow of Legolas kindled in the air as it flew,
and plunged burning into the heart of a great wolf-chieftain.
All the others fled. -J.R.R. Tolkien, The Lord of the Rings