Alchemist's Fire Projection Device

Two-handed, heavy, loading.
This weapon must be loaded with alchemist’s fire to work.
It can hold up to 3 flasks of alchemist’s fire. To load a new flask a creature within 5 feet of the device must use a bonus action to transfer the contents of a flask into the device’s chamber.
A creature wielding the device can fire it as an action, causing a gout of flame to shoot out in a cone 30 feet long and 15 feet wide.
A creature in this cone must make a DC17 Dexterity saving throw or take 3d8 fire damage for every flask loaded into the device when it is fired, and are also set on fire. A creature on fire takes 1d4 fire damage at the start of their turn unless they or a creature within 5 feet uses an action to douse the flames.