They are the toughest enemies in the maze, even to those who are at an appropriate level for the dungeon, and have a lower encounter rate than most other enemies, only be fought in the later rooms of the dungeon. When they get low on health, they cast Meteor, a highly devastating attack. If the player has a job level 99 Thief, they can steal a Protect Ring, although they may end up with an Elixir instead. When defeated, this enemy has about an 11% chance to drop a Protect Ring.
If the party's level is low, they shouldn't try and fight King Behemoths unless they get a preemptive strike. It's best to use your strongest attacks and spells while having your Devout heal the team when the need arises.
Be careful not to use too much high-level MP when fighting King Behemoths, unless you're only fighting these terrifying creatures for the purpose of grinding.
Behemoth is a beast mentioned in Job 40:15–24. In addition to mythological creatures, it is likened to elephants, hippos, rhinos, and bison. Metaphorically, the term behemoth denotes "an extremely large or powerful entity."