Guard Stan:
Want a Silver Dryad, eh?How's this: I'll give you one Silver Dryad in exchange for five Silver Fairies and five Silver Golems. Or we can play a game and you might win better odds? Up to you.
"The normal rate should be fine."
"Let's play." [Guess correctly in two tries - 3 silver fairies]
"Let's play." [Guess correctly in three tries - 7 silver fairies]
"Let's play." [Guess correctly in four tries - 9 silver fairies]
"How does this game of yours work?"