Zombies are fresh corpses animated by dark energies. Their stiff, rotten muscles make them slow and clumsy, although they are resistant to harm and can take a lot of punishment.
Summon - Unit was summoned and belongs to another world.
Illusion Immunity - Unit is immune to illusions. It can see invisible units and illusory attacks do not ignore its armor.
Undead - Unit is immune to Mind and Death effects, poison and sneak attacks. In addition they suffer damage from Positive energy and are healed by Negative Energy.