How to Easily Defeat the Deep One in Octopath Traveler 2

Loathsomeness waits and dreams in the deep,

At the bottom of the Ivory Ravine lurks a monster that would be equally at home in the black void between the stars. It is the Deep One, and it wants you dead. Kill it first. Here’s how to defeat the Deep One in Octopath Traveler 2.

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How to Easily Defeat the Deep One in Octopath Traveler 2

If you’re completing all the dungeons in Octopath Traveler 2 or just happened to hear of a missing girl from a worried mother in Gravell, you’ll need to take on the Deep One. Fans of the original Octopath will remember this monster, and in Octopath 2, it remains just as strong. This massive octopus offers no quarter, and it can be quite a challenge to bring down.

Here’s everything you need to know.

The Deep One’s Weaknesses and Stats

Here are the Deep One’s stats, weaknesses, and attacks.

  • HP: 138,000
  • Shields 1: 10
  • Shields 2: 13
  • Weakness 1: Sword, Axe, Fire, Holy
  • Weakness 2: Polearm, Dagger, Bow, Ice

Attacks

  • Attack – single member attack that does over 1,000 damage.
  • Slow Motion – inflicts slow on the entire party for three turns.
  • Strike of Despair – single party member attack that does 2000 damage and inflicts silence.
  • Call of the Sea – team hit attack that does 1600~ damage while restoring 6000 HP.
  • First Calamity – attack that hits the entire party for around 600 damage. Eludes to its Eldritch inspiration with its starfall design.
  • Second Calamity – attack that hits the entire party for around 700 damage.
  • Third Calamity – attack that hits the entire party for around 1000 damage.
  • Fourth Calamity – attack that hits the entire party for around 1400 damage.
  • Fifth Calamity – attack that hits the entire party for around 2000 damage.
  • Sixth Calamity – attack that hits the entire party for around 3000.
  • Great Calamity – the entire party is reduced to 1 hp.

How to Beat the Deep One in Octopath Traveler 2

So, this is essentially a timed fight. Once you reach the point of Great Calamity, the Deep One’s signature move, your entire team will be reduced to 1 HP. The Deep One also becomes quicker as the fight goes on, and will then likely follow up with a second and third attack. It doesn’t matter how many Rise Again you have at that point.

Fortunately, there’s a way to end this fight very quickly. Like, finish it in two rounds, no damage quick.  

  • Warrior (Throne). Equip Support Skill Boost-Start (Merchant), A Step Ahead (Inventor), Deal More Damage (Armsmaster), and Peak Performance (Armsmaster).
  • Armsmaster (Hikari). Equip Support Skill Deal More Damage (Armsmaster), Boost-Start (Merchant), A Step Ahead (Inventor)
    • Hikari must also know the Learned Skills Drive Back and Last Gasp.
  • Inventor. Equip with Support Skill Boost-Start (Merchant), A Step Ahead (Inventor)
  • Scholar (Temenos): Equip with Support Skill Boost-Start (Merchant), A Step Ahead (Inventor)

For accessories, speed and attack boosting items are ideal. Alternatively, Finisher’s Claw on Hikari or Throne,

!!Important!! For this build to work, Hikari needs to have as close to 1 HP as possible. The easiest way to do this is to let Hikari die, then use Temenos’s Revive or have Hikari lose a duel.

Our goal is to break the Deep One within the first round. Then we’ll defeat him in the second.

Set the time to night and have Temenos in your party so you get the Blessing of Darkness. The order of the first round isn’t important, so don’t stress it.

Round 1.

Have your Inventor use Critical Scope. This will turn all damage dealt to a single foe into critical damage for four turns. If you don’t have Critical Scope yet, check out our guide on how to get it below.

For Warrior Throne, use her Latent Ability and Aggressive Slash. This will break three of the Deep One’s shields. Use Aggressive Slash again. Do not use her BP.

Related: How to Obtain Job Skills for the Inventor in Octopath Traveler 2

Third, Armsmaster Hikari needs to use the learned skill Drive Back. Drive Back is a polearm based move that can be learned from the Guard in the New Delsta: Backstreets. This move will cause the Deep One’s turn to be moved to the back of the line. Do not use his BP. This will prevent the Deep One from ruining our setup, but if you have a high-level team, it might not even be necessary.

Fourth, Temenos must use his latent ability and Elemental Barrage. This will break the remaining four shields of the Deep One… if you’re lucky. It’s possible that it will only hit three times. If that’s the case, you’ll need to use the turn of the next unit to break him. Again, don’t use BP.

Round 2.

Once the Deep One is broken, use all of Throne’s BP to use Aeber’s Reckoning. You should get some substantial damage. The Inventor’s move doesn’t matter as much, just aim for the largest amount of damage possible.

What does matter is Hikari’s next move: Last Gasp. This move can be obtained in Montwise from the guard at the entrance of the town. He’s only there during the day. If you’re struggling to bring down this guard, use six Bottle of Nightmares, which can be bought at the Black Market.

Last Gasp will unleash a powerful sword attack on a single foe. The lower your HP, the more potent the attack. And since Hikari’s HP is at 1, well… Expect big numbers. This move should be enough to bring down the Deep One, especially if you were able to use Aeber’s Reckoning beforehand. But so long as you were able to do at least 100,000 total damage, you should be able to bring down the Deep One before he gets too far into his Calamities.

Good luck! And if you’re curious, this build does work on most bosses. But if you want to get a few more levels first, check out our guide here: The Best EXP and Leaves Farming Guide for Octopath Traveler 2.


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Author
Daphne Fama
A Staff Writer at Prima Games since 2022, Daphne Fama spends an inordinate amount playing games of all stripes but has a soft spot for horror, FPS, and RPGs. When she’s not gaming, she’s an author and member of the Horror Writers Association with a debut novel coming out in 2025. In a previous life, she was an attorney but found she preferred fiction to contracts and forms