Acid Charge Phial

This small obsidian phial is full of enchanted gunpowder and glows a noxious light green. When inserted into a weapon designed to accept Elemental Charge Phials, it turns that weapon's elemental damage die into acid damage. Additionally, the wielder can cast Acid Arrow at 5th level as many times as the weapon has charges left without using any material components. The method the charges replenish depend on the weapon, but while the spell cannot be cast without any charges remaining, the extra damage still applies.

Notes: Damage: Acid