Leviathan uses Water based attacks either against the whole party or a single member of it. Leviathan uses a powerful Tidal Wave attack as the first move the instant the battle starts, and throughout the battle as well. Waterga is used on a single character for high damage. Its Aqua Breath attack deals moderate damage against the whole party. On the other hand, Leviathan is very easy to damage, making this fight somewhat easier.
It is recommended to have the party on a high level, preferably above level 50. A good job setup is to have a Warrior at Job Level 15 or higher who has learned Focus; a White Mage who has Curaja, Shell and Haste; a Dark Knight; a Monk at Job Level 17 or higher or a Black Mage with Magic Font.
At the start the player should buff the party with Shell, Protect, War Cry (Warrior), and Haste. The Warrior and Monk should use Focus three times and when Focus is fully charged, the Monk should deploy Dropkick and the Warrior should use Strike, or Double Attack if the Warrior has a Job Level of 20. A Black Mage casting Thundaga along with Magic Font will blast about 4000 damage from Leviathan. The Dark Knight should use Draw Attack so if Leviathan uses a move that hits a single character, the Dark Knight will be the one to take the hit.
Leviathan (Biblical Hebrew לִוְיָתָן or לווייתן Liwyāthān) is a violent sea creature referred to in the Hebrew Bible as well as the Talmud and some other ancient Jewish texts. During the golden age of seafaring, the term Leviathan became synonymous with any large sea creature, sometimes describing whales. Bible scholars interpreted Leviathan to be either a demonic sea creature and an enemy of God.
The Talmud and other ancient Jewish sources refer to Leviathan more specifically as a sea serpent, sometimes with multiple heads capable of breathing fire, that was made on the fifth day of Creation. It is said that during the end of days, God will make tents, or sukkah, out of the skin of Leviathan for the righteous to live in. Some have speculated that Leviathan was based on a real animal, the most popular theory being the Kronosaurus and the Nile crocodile.
Being mentioned in the Final Fantasy series as the King of the Seas, its incarnation also appears to derive from the legends of the Shinto god Ryūjin or Owatatsumi, said to be the dragon god that reigns over the seas. This is further reinforced by the parallels of the Leviathan faith of Wutai in Final Fantasy VII.
In some cultures it is believed Leviathan lives at the bottom of Mariana Trench.