On Wizardry
Dendra's 'On Wizardry' is a reference book meant to explain the intricacies of magic to non-mages. Prior to its publication, even a basic understanding of magic was practically impossible to obtain, unless one were actually in training to use it. Mages throughout the Mage Wars tended to be very secretive, unwilling to share techniques with "the ungifted". While not a teaching grimorie, Dendra's work made it possible for many lesser mages to discover their potential, while also making the first scientific studies of magic possible.
Like many similar works, the name was kept, the actual work itself was expanded upon and copied down through the Ages. Many things Dendra only speculated on were later corrected, and different schools of magic Dendra himself did not have access to were added. The initial publication was eight volumes, by the end of the Alliance-era, the full set came in at twenty-one.