Potion of Longevity

When you drink this potion, your physical age is reduced by 1d6 + 6 years, to a minimum of 13 years. Each time you subsequently drink a Potion of Longevity, there is 10 percent cumulative chance that you instead age by 1d6 + 6 years.
Suspended in this amber liquid is a tiny heart that, against all reason, is still beating. These ingredients vanish when the potion is opened.