Elixir of Immortality
Elixirs of Immortality are the most prized creation of the Alchemist's Guild. When imbibed, these potions are able to restore youth to its drinker.
Most of these elixirs restore a scant few years of life, but remain incredibly rare. The most powerful can fully restore an individual to their youth, and are the sort of thing that kings empty their nations coffers for.