Steel tank
A steel tank is an instrument of war. Each city-state has the ability to capture a fiery spark from Jeramun, contain it within a strong metal tank, and cultivate it into a powerful fire elemental spirit. A city may tend up to five tanks at a time in this manner in preparation for battle. Slaying adventurers during a sanctioned raid charges it, allowing soldiers to unleash a fiery conflagration capable of destroying locations in an enemy city.
Imbuing an empty tank with an artefact spark changes a steel tank into a repurposed spark tank.
Steel tanks can be forged by any adventurer suitably skilled in armoursmithing.