Manuals of Advantageous Exertion

Wondrous Item, Very Rare, 30,000 gp

These handwritten books contain exercises and insights into improving your ability scores. Their words are charged with magic. If you spend 48 hours over a period of 6 days or fewer studying a book’s contents and practicing its guidelines, one of your ability scores increases by 2, as does your maximum for that score. The ability that increases is shown on the Manuals of Advantageous Exertion Type table. Afterward, the manual loses its magic, but regains it in a century.

Manual of Advantageous Exertion Type