Unstable essence is a type of essence that can be turned into Runecrafting experience by using it on any Runecrafting altar (except for the Ourania Runecrafting Altar). The essence provides only experience and does not yield runes. The player needs to have at least 10 unstable essence in their inventory when attempting to imbue runes, as 10 essence is used at a time.
Experience values per one unstable essence are the same as imbuing runes with pure or rune essence. Crafting runes through the Abyss or with the Demonic skull buff active does not boost the amount of experience received while using unstable essence. Unlike pure or rune essence, however, unstable essence is stackable and rapidly consumed, yielding fast Runecrafting experience in the process. Unstable essence is converted into experience in stacks of ten every 0.6 seconds, and up to 60 stacks are converted in a single interaction.
Unstable essence can be used with Runecrafting urns.