Acid

Acid was a caustic liquid that could cause major and permanent scarring and possible death. The fumes of most acids were poisonous to breathe. It was more damaging to most objects than either fire or electricity. Certain creatures, perhaps most notably black dragons, were known to spray or "breathe" acid from their mouths.

Uses
Acidic liquids were typically created by spellcasters with training in alchemy and sold by alchemists. A vial or flask of acid, suitable for throwing as a weapon, could be purchased for about 10 gold pieces or as much as 25. A shattering flask or vial of acid could splash as far as.

Acid was a component in many spells, such as acid storm, acid bolt, or venomfire. Magic weapons could be imbued with the acidic burst property to make them more damaging.

History
The Do'Urden patron and weapon master, Zaknafein, while transformed into a Zin-carla, willingly fell into a pit of acid to prevent himself from murdering his son, Drizzt. In this battle, Guenhwyvar, Drizzt's magical panther, also fell into the same chasm, but, escaping and healing in the Astral Plane, Guenhwyvar made a full recovery.