Acid Elementals are composed of living acid. While vulnerable to enemy attacks, they still are dangerous, as their attacks cause ogoing damage.
Summon - Unit was summoned and belongs to another world.
Venomous - Unit's attacks apply additional Poison damage unless a Fortitude save is made.
Acid Immunity - Unit is immune to Acid damage.
Elemental - Unit is immune to Mind-affecting effects, Critical hits, poison and sneak attacks.
Illusion Immunity - Unit is immune to illusions. It can see invisible units and illusory attacks do not ignore its armor.
Poison Immunity - Unit is immune to Poison.