Air Elementals are composed of wind and storm. They can fly, are invisible and completely immune to normal ranged weapons and electrical attacks.
It is not mentioned in description, but this unit can use Sneak Attack.
Flying - Unit can fly, which negates all terrain penalties. A Flying unit can not be attacked by non-flying units in melee, athough they do counterattack. Some melee attack and units with Long Reach ability can reach flying units too. Invisibility - Unit is invisibe. It cannot be targeted by uits without Illusion Immunity. unless it attacked this turn. Summon - Unit was summoned and belongs to another world.
Electrical Immunity - Unit is immune to Electrical 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.
Missile Immunity - Unit is immune to all Mundane ranged attacks.