Wondrous item, common
Basically, one of these Ember Seed magic items are rare, bright orange seeds has been imbued with the incinerate chemicals which shall ignite when the pierced or smashed. Actually, this shall make them dangerous, but the magical ammunition whenever it is used in the blowgun, sling, slingshot, or seed shooter. But whenever it is using the ember seed like the ammunition, the attack inflicts the fire damage instead of this bludgeoning damage. However the hit shall target must be succeeded on a DC 12 Dexterity saving throw or be ignited. But any type of creature by the resistance or else the immunity for being firing the damage automatically succeeds on this specific save. Of course the ignited creature shall take 1d6 fire damage at an end of each of its turns, but it could use its action for ending this condition.
Usually, an ember seed is destroyed after it hits a creature.