This urn is chipped from a single chunk of obsidian. It has a tightly fitting lid, weighs 4 pounds, and appears to hold up to 1 gallon. It can contain any material or liquid no matter how hot, without cracking or even heating up, as long as it fits within the urn.
While you are attuned with the urn an action you can speak the command word and expend a number of charges to cause the urn to glow with a red light in the facets across its surface, burning all creatures that come near it for the next minute. Any creature (not including you) that ends its turn within 5 feet of the urn must make a Dexterity saving throw. If you are not a caster this uses your Constitution as your casting ability. The creature takes 2d6 fire damage on a failed save, or half as much damage on a successful one. If you thrust the urn at a creature as an attack action that creature must make the saving throw against the sphere’s damage
When you activate the urn with 2 or more charges, the damage increases by 1d6 for every charge above 1. The urn has 5 charges and regains all expended charges each dawn.