Ketos (also called Ocean Master Ketos) is the guardian of the Undersea Grotto, fought at B8F (The proud, tall waves).

This huge, ancient whale is a faithful servant of the king of the Deep City, and is capable of telepathy. Even so, he is treated with great respect, by both the said king and his other servants. Although unwilling to fight the explorers, he does so, as it is his duty as the guardian of the city. After they defeat him, he shows respect toward the explorers, calling them "great ones".

Ketos (Etrian Odyssey III)Edit

A grand white whale that slumbers in the abyss. It uses Telepathy to speak with explorers.
Enemy Data
HP 4699
AT 32
DF 32
EXP 9905
Skills Great Melody, Ocean Rave, Spout, Grand Berry, Freeze Ripple
Items Whale Fumarole, Tough Membrane (Conditional)
Weakness Fire
Resistance Ailments and binds
Immune None
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Ketos will use Spout on the first turn and subsequent turns that are multiples of 5. This increases his speed and evasiveness. Ketos will continue doing so until his HP has been brought down to red.

Between those turns, Ketos will use various attacks.

Freeze Ripple is a multi-target ice attack that has a chance to leg bind the party members it hits. This is important to note, because another powerful skill, Ocean Rave, will only hit party members that are bound.

Grand Berry is a single target hard-hitting attack that may paralyze.

Once Ketos' HP has been brought down to red, he will start using Great Melody, a skill that can put party members to sleep. He will also stop using Spout and will use his attacks more randomly.

It is a good idea to use Metopons or a Prince's Ad Nihilo to nullify Spout. It is also highly beneficial, though not necessary, to have a Monk with a Level 4+ Unbind. This will prevent at least some of the party from getting hit by Ocean Rave. Grand Berry usually targets the front row, so keep your weaker party members in the back. Be prepared when Ketos starts using Great Melody since this makes the fight more unpredictable.

Skills Edit

  • Spout (Uses Head): Self buff, increases evasiveness.
  • Freeze Ripple (Uses Legs): Deals moderate ice damage to the whole party, may inflict leg bind.
  • Ocean Rave (Uses Head): Deals heavy Strike damage to party members with leg bind.
  • Grand Berry (Uses Head): Powerful single target Strike damage, may inflict Paralysis.
  • Great Melody (Uses Head): Hits the whole party, puts party members to sleep.

Drops Edit

  • Whale Fumarole (Worth: 913 en)
  • None.
  • Tough Membrane (Worth: 10000 en)

Conditional Drop Edit

  • To get Ketos' conditional drop, the Tough Membrane, you have to kill him in one turn.

Trivia Edit

  • Ketos (sometimes latinized as Cetus) is a reference to a whale monster in greek mythology of the same name, often described as a gigantic whale or shark, who was fought and defeated by Perseus and Heracles. The term Cetacean is also derived from the latinized version of this word.
  • Ketos is one of the few monsters in the entire series shown to be capable of human speech, albeit via telepathy. Other ones include Alraune and the Master Bird. Manticor is also said to be able to speak but is never shown doing so.