|“||And he asked him, 'What is thy name?' And he answered saying, 'My name is Legion, for we are many.'||„|
— A soldier, quoting Mark 5.9, naming the Legion as they swarm over Gamera (Gamera 2: Attack of Legion)
The Legion get their name from a comment a soldier made in the film; quoting the Bible, "And Jesus asked him, 'What is thy name?' He replied, 'My name is Legion, for we are many.' Mark 5:9"
The Symbiotic Legion, as noted in the movie, are silicon-based alien lifeforms. Legion's exterior greatly resembles that of an insect, especially that of a Rhinoceros Beetle, with a single eye and pincer-like mandibles. The Legion do not actually have muscles. Instead, they are able to move through pressurized gas that passes through their seemingly hollow exoskeleton. The Symbiotic Legion consist of hundreds of smaller Soldier Legion (ソルジャーレギオン?), and a single gigantic Mother Legion Sorujā Region (マザーレギオン?). The Legion possess a symbiotic relationship with a giant 100-meter tall flower called the Legion Plant Mazā Region (レギオンプラント?) or Pod Region Puranto (草体?). The Legion cultivate and defend this plant, providing it with oxygen released from the breaking down of silicon compounds on which the Legion feed. After a certain point, the plant will launch a seed into outer space, spreading the Legion species to other worlds. When the plant seeds, it will produce a powerful nuclear-force explosion capable of vaporizing the entire city of Sendai. Sōtai
The Mother Legion's body structure is similar to crustaceans. Her body tissue is based on silicon and has a semiconductor-like structure. She is durable, able to withstand a frontal assault from the J.S.D.F. and resist Gamera's Ultimate Mana Blast for several seconds. She possesses usable insect-like wings that give her the ability to fly, despite her enormous size (though after flying off to start a new hive, she sheds her wings when attacked and reverts to a subterranean lifestyle). The Mother Legion sports multiple egg-cases in her abdominal region which house Soldier Legion which she can dispatch at will. If the Soldiers are unable to protect the plant, she will guard its location. The Mother's eyes turn red when she is angry or injured.
The Symbiotic Legion arrived on Earth in a meteorite that crashed near Sapporo. The meteorite caused strange lights to appear in the sky, and also drastically elevated the oxygen levels in the surrounding air. Two Soldier Legion raided a nearby brewery, where they disintegrated the glass on the beer bottles to absorb the silicon. Eventually, the Legion congregated in the subway under Sapporo, where they attacked a train and brutally killed several passengers. In the tunnel, the Legion planted a giant flower, which grew rapidly and eventually broke up through the street and became prominently visible. The J.S.D.F. formulated a plan to place C-4 charges on the plant's roots, hoping the explosion will ignite the oxygen-rich air and destroy the plant in a fiery explosion. However, the explosion failed to destroy the plant. Suddenly, Gamera arrived in the city and destroyed the plant with his plasma fireballs. In response, a swarm of Soldier Legion climbed onto Gamera, biting through his shell and drawing blood. Before the Legion could kill Gamera, they were attracted to a nearby electrical transformer, which electrocuted them all to death. Gamera flew away to recover, but the gigantic Mother Legion suddenly emerged from underground and flew away. The Mother Legion was apparently shot down by the air force over the ocean, but no body was ever found, only a wing.
Suddenly, the Symbiotic Legion and their queen appeared in Sendai, where a new Legion Plant had been cultivated. Anticipating the flower to seed and destroy the city in a catastrophic explosion, the citizens of Sendai attempted to evacuate in helicopters from the city's airport. As the last helicopter, on which Asagi Kusanagi was present, prepared to leave, the Mother Legion erupted from the ground and tried to destroy it. Thankfully, Gamera arrived once again and distracted Legion long enough for the helicopter to escape. The Mother Legion proceeded to brutally injure Gamera, impaling his chest with her horn and blasting off his shoulder with a plasma beam. Aware the flower was about to seed, the Mother Legion retreated, leaving the wounded Gamera in the blast radius. With no time to lose, Gamera approached the flower and threw his body in front of it just as it seeded, preventing its pod from being launched into space, but annihilating Sendai and apparently killing himself in the process.
The Mother Legion and her swarm later arrived in Tokyo, intending to plant another flower. The J.S.D.F desperately tried to halt the Legion's approach, but their weapons had no effect. Gamera, miraculously revived by the Earth's Mana, flew to Tokyo to battle the Mother Legion. Meanwhile, the Soldier Legion were lured to an electrical plant, where they climbed onto the power lines. The J.S.D.F. wasted no time in blasting the stationary Legion with missiles, eradicating them all. Gamera managed to tear off the Mother Legion's horn, but she was far from defeated and proceeded to bombard Gamera with deadly red energy strands fired from her head. Out of options, Gamera absorbed a huge amount of the Earth's Mana and opened a cavity on his chest, out of which he fired the Ultimate Mana Blast. The powerful beam collided with Legion, pushing her back as she tried to withstand it. Finally, the blast was too much and Legion was completely vaporized, ending her species' conquest of Earth.
Although the Legion do not make a physical appearance in Gamera 3: Revenge of Iris, the Mother Legion's demise at the hands of Gamera's Ultimate Mana Blast is revealed to be responsible for draining Earth's Mana, allowing the film's secondary antagonists, the Hyper Gyaos to emerge in vast numbers all over the world.
- The Mother Legion can recognize electromagnetic waves of all wavelengths.
- Legion can fire a blue beam of focused microwaves from the Mother's nasal horn. It can also fire the Butte Legion by opening its horn, a beam which possesses major destructive powers, being able to destroy a manufacturing facility with a few blasts, and even put holes in Gamera's shell. It is sharp enough to leave cuts in Gamera's body. It should be noted that Gamera's hands were burned when he ripped off the top part, implying that this heats Legion's shell to an extremely high temperature.
- Legion can produce up to 100 Symbiotic Legion Soldiers an hour from the red egg chamber on the Mother's abdomen.
- The Legion's Tunneling Arms serve the role of excavators allowing Legion to burrow underground.
- Mother Legion's legs have incredibly sharp tips which are capable of cutting through many different materials, and are easily able to injure Gamera by being able to break through his shell.
- The Mother Legion has two legs with sickles attached to them. It is possible to attack the enemy from underground with them and they have a wide range of motion.
- The Mother Legion is covered in an insulating material similar to rigid silicon resin. Highly durable, to the point that it survived the Mana Blast for several seconds.
- The extra clawed limbs that form a crown around Mother Legion's head can produce different types of electromagnetic waves to deflect missiles and neutralize Gamera's fireballs. If they are damaged, however, they cannot completely counter strong projectiles.
- Using the Nasal Horn and the Interference Claws, the Mother Legion can create an electromagnetic field to counter Gamera's plasma fireballs.
- If the Mother's nasal horn is torn or blasted off, she can produce crimson laser tendrils from the resulting wound. They can move about freely and have extremely high temperatures, letting them cut through Gamera's shell easily.
- Main article: Legion/Gallery.
- The Mother Legion is the second female monster to appear in the Gamera series, the first being Jiger. She would have been the third, if Gamera vs. Garasharp was ever released.
- When she is attacked, the Mother Legion sheds her wings and takes up a subterranean lifestyle. This is similar to real-life ant queens, which only fly once in their lifetimes to disperse to a new location, then snap their wings off once they have established a colony.
- The Mother Legion is by far the largest monster Gamera has ever fought.
- The Mother Legion is the last space monster in the Heisei Gamera trilogy.
- The Mother Legion and her soldiers are the only kaiju in the Heisei Gamera series to be extraterrestrial in origin. The others, Gamera, Gyaos and Iris are all Atlantean in origin.
- One of the concept drawings for Orga's design bears a suspicious resemblance to the Mother Legion.
- Mother Legion's roar sounds similar to the M.U.T.O. from Legendary's Godzilla.