For example,:
From Book 43, Chapter 19, Stanzas 19-26 the recorded utterances of Joachim the blessed and completely sane, High Prophet of our divine lady, honored be his memory for all time:
"Get away from me with that thing! You can't turn ME into a goatherd, no you mayn't, not with your ever-scratching pen and your sheets of skin! For you won't be the last person to scratch, far from it. They'll hear them first: the scratching from beneath the mountains, the echoes in the avalanche and the vibrations in the boulders as the land begins to grind! They come, and they scream as they are birthed. The home of the girl who marries the wind is the third to be devoured, spiraling beneath claws that rise through the night. They'll flee, you see, flee in every direction but down - and the roads will be choked, and the knights will be choked, and all will waste away. If they're smart they'll seek the goatherd, the first goatherd, for she knows the song that can stop the scratching in the place where heartbeats cease. And their little hooves will go clip clip clop like when I used to be a little goat, and O goodness mee I think perhaps I may wish to lie down, put down your quill and fetch me my O dear"
<The ink in this section is smudged>
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Man, those are fun to write. The trick is to put in a whole bunch of vague clues that almost make sense right now, but which can be interpreted multiple ways. For bonus points, allude to the heroes in the prophecy, but not in a way that screws you if someone drops out of the campaign.