Source: The Book of Many Things

Weapon (any bow), rare (requires attunement)

Ammunition fired from this bow blazes brightly. When you hit with an attack roll using this bow, the target takes an extra 1d6 fire damage. If the target is a flammable, nonmagical object, it catches fire, taking 1d6 fire damage at the start of each of your turns until a creature uses an action to extinguish the flames.