Fire Fire!
This hollow metal crossbow was created by a team of kobolds and contains an enchanted ember at its core. The crossbow has 3 charges. While the crossbow has at least 1 charge, the inner ember burns brightly when you hold the weapon. While it burns, the crossbow emits bright light in a 20-foot radius and dim light for an additional 20 feet, and any nonmagical bolt fired from the crossbow catches fire and deals an extra 1d6 fire damage to any target it hits.
You can expend 1 of the crossbow’s charges as an action to cause the ember to spew forth devastating flames, sending out a wave of fire in a 30-foot cone. Each creature within the cone must make a DC 15 Dexterity saving throw. A creature takes 4d6 fire damage on a failed save, or half as much damage on a successful one. The fire ignites any flammable objects in the area that aren’t being worn or carried.
The crossbow regains 1d3 expended charges daily at dawn. If you expend the last charge, roll a d20. On a 1, the magical ember inside the crossbow dies, and the weapon becomes a nonmagical crossbow.
The kobolds were up to something. They were huddled together, squabbling over a pile of metal scraps. Occasionally one of them would shriek in pain, and the smell of cinder and burnt leather would fill the air. It went on like this for days. There were the occasional breaks whenever one of the creatures would lose a toe doing something careless, but their strangely intense focus would resume before too long. If it weren't so out of character, it would have been exciting. Instead, it was worrying. A week went on. Then two. From the depths of the caves, what had grown into a steady stream of quiet bickering and gibberish turned suddenly chaotic and unhinged. Screams started pouring out from the tunnels, followed by a parade of the badly burnt kobolds, calling out in a mix of terror and euphoria. Loosely translated, the calls of "Fire! Fire!" were heard from beyond the mouth of the cave. With a manic grin upon its face, one kobold strode through the caves after its fleeing brethren, brandishing a metal crossbow and spewing fire.