A One-Round Adventure for 4th - 6th Level Characters
Crimson Codex Faction Adventure 4
From the introduction:
During its operations in Xen'drik, the Crimson Codex has accumulated an extensive collection of tomes, books, scrolls, magic items, and other records going back to the Age of Giants and beyond. Ohnal Caldyn and his immediate circle of scholars have taken the most important of these artifacts back to Khorvaire for study. The ones that looked to be of less relevance were studied briefly and then placed in a holding library known to the Crimson Codex as the "Tomb of Tomes".