You expend your transmuter's stone to prime a cauldron full of liquid, up to 1 pint, to receive magical energies. Within the next hour, you or someone you designate must cast a ritual or non-ritual spell with a range of Self or Touch while touching the primed cauldron of liquid. The primed liquid becomes a potion invested with that spell, and the spell effect will activate when the liquid is consumed.
For a liquid to become an active potion using this spell, the liquid must be composed of the proper component recipe. Transmuter wizards experiment for years to create their potion recipes, and rarely share them. They are much sought after magical formulae often scribed into spell books. 1 pint of liquid is sufficient to create 2 cups of potion. Each cup of potion is a single dose.
If cast at higher spell levels, you can prime a larger volume of liquid components. As a 7th level spell, you can prime 1 quart (2 pints or 4 cups). As an 8th level spell, you can prime 2 quarts (4 pints or 8 cups.) As a 9th even spell, you can prime 1 gallon (4 quarts or 16 cups.)
* - (transmuter's stone, an iron cauldron, and the appropriate component recipe)