The Erginus is a giant lizard-like creature that first appeared in Earth Defense Force 4.1: The Shadow of New Despair.
EDF 4.1 Edit
Erginus first appears suddenly near the end of in Mission 27: Assault. The same one reappears a couple more times throughout story mode -- in Mission 39: Dozing Beast, where it has fallen asleep in the middle of a city; and Mission 53: Crash (which is supposed to be called Clash, but nevermind), where a Balam is finally dropped and the creature is finally slain. However, a large group of them as well as a Mutant Erginus appear in Mission 67: Battle of Giants.
In-keeping with 2025 and 4.1's tendency towards being a remake of Global Defence Force, it is similar to the Saurous / Solas monster, with Godzilla-like physical and breath attacks. It is said to have risen from the ocean at some point during the war of 2025, but Ohara later claims that they must have come from outer space, from a planet where they were the apex lifeform: presumably this means they were deployed in the normal Ravager fashion of dumping things in the ocean and letting them walk ashore by themselves. In response to the arrival of the vicious Erginus, the EDF introduced the giant Walking Fortress Balam, which, while not built to take them on specifically, has the necessary equipment to fight them - simple brute force.
A large, mutant Erginus exists, twice the size of any other. Ohara, the Ravager Researcher announces that he believes this to be the actual adult form of the Erginus, and that all others seen before must be juveniles. This one has red skin instead of brown (making it appear quite similar to a Vallak) and its glowing sections now glow yellow instead. As with all mutants, it is much stronger than the regular variety, to the point where Intel urges the Balams to focus on this threat instead of the various other Erginuses remaining.
In its first two appearances, the Erginus proves to be unkillable. Instead the player(s) must survive long enough for it to escape. It appears again, but the EDF drops a Walking Fortress Balam in and player must pilot it and kill the Erginus.
Despite killing this Erginus, several appear at once in one final mission. The player or players are tasked with assisting a large force of NPC Walking Fortress Balams as they battle the Erginuses, protecting the Balams from giant ants, first black and then crimson and finally hornets, followed by another wave of regular ants. The main principle of this mission is that the NPC Balams will attack whatever is closest to them, and can become separated and thus much less effective if too many are fighting bugs instead of Erginuses.
Afterwards, a final Balam is dropped with stats depending on the difficulty level (999,999 health on Inferno, more than any deployable Balam) and a player may pilot this to assist in killing all remaining Erginuses alongside the remaining Balams and then kill the Mutant Erginus. On lower difficulties it is quote possible to ignore the Balam entirely and focus on grabbing pickups until the remaining Balams defeat the mutant, but on higher difficulties there will probably be too few Balams left for this to be left to chance. It is highly advised to stick with the group, as the Balam can be knocked down during its getting up animation, leaving it to constantly take damage without having the time necessary to stand back up. The "charge up" (L3) seems to be designed to prevent this, and appears to work something like the "riposte" move for the Fencer; tapping it at the correct time during a knockdown will result in a much faster recovery.
Erginuses can in turn be kept in a constant knockdown state using the uppercut combo (right, right, left, right) since either of the final two hits connecting will floor even the mutant.
Although the player can kill an Erginus without the Balam, this is not recommended as it will take a significant amount of time to do so. An Erginus on Easy has about one and a half times as much health as a Blue Hector on Inferno. On Inferno, even a basic Erginus will shrug off multiple hits from superweapons like the Tempest S1A, Gungnir or Wild Leviathan.
In DLC 2: Exteme Battle there are multiple fights against Erginuses in maps that do not have a pre-placed Balam, and in one case all enemies are Erginuses which would make it very hard for an Air Raider to earn enough credits to drop one. For these missions, the Erginuses have less health than in the main campaign, making the use of normal high-damage weapons like the Epsilon Armored Railgun tenable.
Perhaps most frightening is the addition of a mutant Erginus to the collection of "red" enemies in DLC 2's mission Bloody River on Inferno difficulty. When the mission already contains Red Drones, Red Flight Vehicles, and a Red Death Queen.
Um, good luck with that.
The Erginus has several attacks:
It can also leap at an opponent and can move around the battlefield on all fours.
EDF 5 Edit
A normal Erginus has been shown in the fourth mission of Earth Defense Force 5, a mission very similar to Dozing Beast with the addition of tanks armed with giant Idunn-like cannons which resemble the classic Godzilla Type 66 MASER Tank. It is hit with a strike from Charon Tactical Bombers, but gets up and begins menacing the city. However, the tanks are more than a match for it and soon its menacing ways are bought to an end. Following its defeat, a smaller kaiju-like creature with a spiked back which is not Anguirus appears. This new monster attacks by rolling and performing a very silly belly flop attack.
It is not clear at present whether the use of the unaltered Erginus means the creature will appear in the final game in its 4.1 form, or if the current model is a development placeholder.