Legend Lore: Penumbricon

The Penumbricon, also known as the Leaves of One Night, the Eonic Archives, and the Oshran Record Keeper, were / is / will be a pair of five black slate tiles joined together to open like a book. Engraved on each tile were innumerable silver letters, which appeared like any script known to the observer, and would illuminate to produce information. To go forward or backward a page in the text, the reader would turn one of the black slates over, which would cycle a buried tile over, so as to not be physically made of thousands of thousands of pages.
The text of the Penumbricon included many alternative truths to the creation myths of the multiverse, including many intimate details pertaining to Shar. Any such written text was magically cursed by Shar to be indecipherable, so as to guard her secrets, but when the Oshran Elf adventurers Xillin Xipphulae and Pikyr the Brave found the Leaves of One Night, they conspired together to magically transform the tome into something they could use against the Goddess.
Xillin's son Xerion Shadowmoon would later betray his father, taking the Penumbricon to Shar herself.