Acid rats

Acid rats are a species of acidic rat found in the Underpass. They also exist in other parts of the Underdark, having been present in the mines of Corso's Chasm during the Drow invasion.
Acid rats are in some way descended from oozes, giving them immunity to critical hits. This implies that unlike the base rat, acid rats do not have vital organs and are instead furry bags of cytoplasm.
== Mechanics ==