Mordant Fang (Patreon)

Weapon (heavy crossbow), very rare

A strange firearm that functions by pumping an acid gland of a monstrous creature to fire bolts and bile. You gain a +1 bonus to attack and damage rolls you make with this magic weapon. This weapon has 8 charges and regains 1d8 + 1 charges daily at dawn. Ranged attacks made with this weapon deal an extra 1d4 acid damage.

Caustic Spike. You can spend a charge to have this weapon create its own ammunition and ignore the loading property as a bolt of crystalized acid forms within the barrel. The ammunition created by this weapon deals 2d8 acid damage and dissolves upon impact.

Bilious Vomit. As an action you can spend 3 charges to fire acidic discharge in a line 100 feet long and 5 feet wide. Each creature in the line must make a DC 16 Dexterity saving throw. On a failed save, the target takes 8d8 acid damage, or half as much damage on a successful one. In addition, if a creature that fails its saving throw is wearing nonmagical armor the armor becomes corroded and takes a permanent and cumulative -1 penalty to the AC it offers. The armor is destroyed if the penalty reduces its AC to 10. The acid eats through any nonmagical wood, stone, or metal in its path provided it is no thicker than 2 inches.

At the start of your turn you can spend an additional charge to maintain the line of acid, pointing it in a new direction if you wish.

Once the Colossal Grime Guzzler was felled the time for celebration was short; the real work had just begun. Instantly the mountainous corpse was swarmed by a platoon of harvesters hacking away at its leathery hide to uncover the bounty within. As theorized, even after their host had perished the acid glands confoundingly continued to pulse and produce the same caustic substance that had melted so many of our hunters into puddles of organic sludge. Once a contraption that could properly contain and siphon the acid (after months of trial and error and approximately 3 tons of scrap material), the newfound weapon quickly found itself tested on the field of battle. Early results were promising as jet-streams of corrosive liquid tore holes through metal and flesh alike, though the ensuing stench left much to be desired.