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. Unstable essence may be purchased from Wizard Rinsit's store in the Wizards' Tower in batches of 100 and 200 essence in exchange for Runespan points. Unstable essence can be used with Runecrafting urns.