Mogpendium
“The Mogpendium will prove to be an invaluable resource during the Moogle Treasure Trove, kupo!
Pore over its contents to find the best ways to get your hands on irregular tomestones, then use that knowledge to fill your packs!
And once the weight of your tomestones becomes too much to bear, bring them to me and I'll give you all sorts of rare and remarkable items!
— In-game description
During Moogle Treasure Trove Events (first made available during Moogle Treasure Trove: The First Hunt for Genesis) the Mogpendium contains a list of objectives that players can complete to earn Irregular Tomestones. For more information, see the event page.
The Mogpendium is unlocked by speaking to the Itinerant Moogle. Afterwards, it can be accessed from the Collection feature in the Main Menu → Duty tab.