Manual of Quickness of Action
Wondrous Item,
Very Rare
(cost 20000 gp)
Crafting Components
Water strider’s antennae, essence from an Elemental Plane
This magical book details workout routines for building coordination and speed. Spending 48 hours over 6 days (or fewer) reading and following the book’s regimen increases your Dexterity score and your maximum Dexterity score by 2. The manual then becomes a mundane item for a century before it regains its magic.
Source