Gnomish Flamethrower

Type: Weapon (flamethrower), Uncommon, Requires Attunement

Worn like a backpack or satchel, this patchwork vessel of scrap metal can hold a maximum of 12 charges. Over the course of an hour, you can feed 5 gp of high-quality coal or oil into the backpack, causing it to regain 1d4 + 3 charges.
Flame Spitter. As an action, while holding the flamethrower’s nozzle, you can speak one of the flamethrowers’ two command words, consuming 1 charge causing it to spout a gout of flame in a 20-foot line or 10- foot cone (your choice).
Each creature in the area must make a DC 13 Dexterity saving throw. A creature takes 1d12 + 1d10 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.
Backfire. When you use Dragon’s Breath, if you roll a 10 or higher on both of the fire damage dice, the Gnomish Flamethrower backfires. Each creature within 10 feet of you must succeed on a DC 13 Dexterity saving throw or take 4d6 fire damage as gouts of flame burst from the make-shift hose