It is a dusty rune. That should have been their first clue that it was dangerous.
Found written on a torn single page…
“Lay thee patiently and still upon the ground, contemplating the Leper Star in the firmament, 'neath a crescent moon, ‘midst the graves of a boneyard 'til the G’na-Shennu come crawling up from the foetid earth. Fear them not. Let them rage about thee, casting ghoul-dust from their chalky talons and scalps,'til they calm, and so begin to whisper their secrets. Then shall they solemnly withdraw into the earth once more, in peace."