Leviathan can be learned with 850 job points. Summoning it costs 48 MP and it unleashes Tidal Wave, a water-elemental attack that hits all foes in a large area. It has a speed of 15. Leviathan has a 40% chance of randomly being learned in battle by a Summoner who has not yet learned it and is not KO'd by it, or absorbs at least 1 HP worth of damage. Nullifying the damage does not count.
In the PlayStation version, when summoned, the summoner will sometimes say, "Sea fang, attack with water's power! Leviathan!"