Gunpowder. When fire damage is dealt within 1 inch of at least 1 pound of gunpowder, the gunpowder is ignited, and any creature within 10 feet of the ignition must make a Dexterity saving throw (DC 12). On a failed save, a creature takes 1d6 fire damage for each pound of gunpowder ignited within 30 feet of the creature, or half as much damage on a successful one.

Any fire damage dealt to less than 1 pound of gunpowder causes the gunpowder to flare for 1 round, shedding bright light in a 30-foot radius and dim light for an additional 30 feet, and setting fire to any adjacent gunpowder within 1 inch of it. Gunpowder exposed to water (such as rain or submerged underwater) for more than 1 round becomes destroyed.

Oil. When fire damage is dealt to oil, it starts burning and is destroyed after 6 hours.