Leviathan

The Leviathan series are giant missile launchers exclusive to the Fencer class in Earth Defense Force 2025 and Earth Defense Force 4.1: The Shadow of New Despair, and could be considered the class' equivalent of the Genocide Gun. They require guidance from an Air Raider to fire.

Description
The Leviathan series are back-mounted single-tube cruise missiles which are like an immensely beefed-up version of the Ranger's Prominence missile launchers in terms of their mechanics and effects. They deal more damage than most near-level Air Raider strikes with the Wild Leviathan more powerful than some top-level versions, but they are limited by having no internal targeting system, requiring an Air Raider's Laser Guide Kit or Guide Beacon Gun in order to lock on at all. Their lock-on time is enormous, 25 seconds by default, and they have the smallest lock-on bounding box of any guided weapon, barely larger than the target cursor; since the cursor only appears if it is inside the bounding box, just finding it can be a little tricky. Their reload is surprisingly fast, with the first two taking 6 seconds and the final one just 3.

The missile, when fired, is similar to a Tempest in that it is gigantic, very slow and surprisingly maneuverable. Much like a Prominence missile, it soft-launches and then flies upwards for a few seconds before it starts to track its target. It is massively larger than the launcher model would suggest, and it is essential to ensure clearance around the Fencer when he fires it, since if the tail of the missile touches anything when it appears, it will explode instantly and kill both the Fencer and anyone around them. It is very dangerous to launch the missile in any kind of enclosed space or with enemies very close by, and wise to check for overhead obstacles such as streetlamps and traffic lights before firing.

They do not have either thrusters or a zoom, so the use button does nothing.

Strategy
The Leviathan is the Fencer's most powerful weapon for dealing with boss enemies, Tunnel Exits, Large Transport Ships, Hornet hives and other tough targets. The damage of each missile is incredible and their surprisingly low level means that in online play they can sometimes outright break missions, such as taking down the Argo before it has even finished transforming in Giant Ship on Hard using Leviathan MAs, leaving HQ talking about destroying a heap of scrap metal with air raids for several minutes afterwards.

Since the missile is slow-moving and the target box is tiny, it is unsuited to any target that moves around quickly, and the long lock-on means the Fencer is defenseless for a long period while preparing to fire. If the Fencer and Air Raider are the only two characters it is best to use a Guide Beacon Gun despite the inferior bonuses, so the Air Raider can defend the Fencer from enemy attacks.

The lock-on only takes the full 25 seconds if using the first or second Guide Beacon Guns since these are the only Guide device with a 1x lock speed multiplier; it can get as low as 4.2 seconds if using the top-level Laser Guide Kit. The lowest actual maximum lock-on distance is 450m for a Leviathan, 600m for a Leviathan MA and 1,500m for a Wild Leviathan, since no Air Raider Guide device has a lock distance bonus lower than 1.5.

Because of the soft launch and slow movement, if using a Laser Guide Kit it is safe to lock the missile onto a targeted point very near to the Fencer to make the lock-on process easier, and then shift the aim point to the weapon's actual target when the Fencer has fired. The missiles do not seem to care about their lock-on range after they are fired, and so will go after a Guide Kit's aim point even if it is moved a significant distance away from where they originally locked on to it. Once the missile has pointed itself in the right direction it is possible to stop lasing the target entirely since the missile will respond to a loss of target by flying in a straight line. If the Air Raider starts aiming the Guide Kit again, the missile will instantly re-acquire the lock and head for the new marked location.

Since their turning performance is surprisingly good, a skilled Air Raider with a Guide Kit can manipulate them into going places they have absolutely no business being, such as swinging them upwards to hit the cores of normal Transport Ships or guiding them inside a Quadruped Fortress' hatch. It is also possible to aim them using a Guide Beacon placed on a vehicle or Wing Diver to hit targets that are out of view for direct-fire placement of the Guide Beacon, though this is not likely to end well for whatever the Guide Beacon is attached to.

They can be used offline if the player has a second controller (or a controller in 4.1's PC version if they use the keyboard and mouse for the first character); this is a powerful method on missions like Tower Siege where one character is used to deal with the waves of Hornets while both are used to launch Leviathans at the hive whenever there is a break.

Because they have a similar non-tracking climb to a Prominence missile, Leviathans are virtually useless in underground missions outside of the largest caverns, and trying to fire one is only really likely to kill the Fencer and his entire team with the splash damage.

Variants
"Flight time" is a measure of how long the projectile exists for after it is fired; it is deleted if it has not hit anything before this. The lock-on time and range are baselines used only for multipliers from Air Raider Guide gear, a Leviathan will never lock on by itself.

Trivia

 * Leviathan is a fearsome aquatic monster described in the Biblical Book of Job, though it more generally refers to something enormous.
 * Global Defence Force features a secret final Air Tortoise variant called Leviathan.