The Nonus Reports are a brief primer on the Northlands of Erde, those lands that The Luck of Fools takes place in. They were written by Nonus Octavianus, a human scholar and traveler, 300 years before the events of TLoF, though most of what is included in the reports is still accurate. Some addendums were added by Scaevola Septimus several years before the events of TLoF.
The Nonus reports are not required reading to understand TLoF. Important world elements that effect the story will ALWAYS be explained within the narrative of the comic, though not always immediately!