The indescribable god has awakened!
Beginning of Abyssal God's second phase, Etrian Odyssey III: The Drowned City

Abyssal God full body

Abyssal God is the true final boss of Etrian Odyssey III: The Drowned City. It can be fought on B25F, the final floor of the Yggdrasil Labyrinth, and is by far the hardest boss in the game, and one of the most frustrating and difficult fights in the entire series.

This creature is the final enemy of the explorers and the creator of the Deep Ones. No words can describe this colossal, tentacle ridden abomination. Its only visible part is its head, atop its body, with a huge, gaping maw.

This beast has many forms of attacks. When its mouth is closed, it uses its tentacles to defend itself, showing great skill in countering incoming attacks and restorative powers. However, once it opens its mouth and shows its true form, it attacks with unstoppable rage, using powerful elemental spells and using its huge tentacles and claws to rip apart anything that may dare to oppose its might.


Spoiler Warning: Plot details follow. Read at your own risk.
The Abyssal God is a power-hungry god-like alien being that travels around space, seeking planets to conquer. It creates a new race on it, acting like an invasive species, destroying other predominant life forms until the race becomes the predominant one (with the races created by the Abyssal God also worshipping it as a deity). It went unstoppable for eons until another being, known as the Yggdrasil Tree, a sentient, highly powerful tree, started chasing after it in order to put an end in its rampage. In order to escape the creature landed on the earth, where it found refuge under its vast oceans and soon created a new race, the Deep Ones, in order to start a war with the planet's dominant race, humans. However, the Yggdrasil soon followed its lead, and landed on the same spot as the monster, quickly growing roots and sealing it within a labyrinth. Now sealed deep into the sea, it simply lies in wait for an opportunity to finally break free and restart the cycle of destruction.

Abyssal God (Etrian Odyssey III)Edit

Strategy Edit

Before the battle starts, it's highly recommended to destroy the several tentacles scattered around the floor, as for each tentacle killed prior to the battle, a portion of its HP will be automatically depleted in the start of the fight. With all of them killed, it will start with around 10% of its HP left, making the first phase of the fight much easier and faster. Plus, its defensive power will be lowered, so that you can kill much faster. Be careful however, as each turn it has a chance of reviving one of its tentacles, recovering 1000 HP and regaining some of its lost defenses. Finishing the first phase in a single turn is the ideal outcome, but you can still kill the boss as long as you don't give it too much time to respawn its tentacles.

Also, keep in mind that the battle has a time limit of sorts. Once the fight reaches 40 turns, the Abyssal God will go berserk, permanently changing to its offensive form and gaining a massive boost in its attack power and becoming unpredictable. For that reason, you may need to adjust you party, in case you are using a overly defensive team or you are having trouble finishing off the boss quickly enough.

Other things that can help against this eldritch monstrosity are skills that protect against elemental damage (a Hoplite's anti-element skills or, preferably, the Zodiac's elemental prophecies for example), as well as character who can dual wield. While not necessary, a character with the Hoplite's skill Overwatch can also help with the earlier stages of the fight. Having the Regroup Tactic limit also helps avoiding status effects and greatly lowering the amount of luck required to beat this boss.

Abyssal God
Abyssal god 1
Enemy Data
HP 10000
ATK 87
DEF 71
Skills Magma Ocean, Ice Tempest, Proton Thunder
Items None
Weakness None
Resistance Physical, Elemental
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During the first phase combat, the Abyssal God will use 3 elemental attacks on the party (Magma Ocean, Ice Tempest and Proton Thunder) for massive damage. Unless you can finish it off quickly, you will need means to block the elemental damage coming from said attacks. Another thing to keep in mind is that, while the boss has an attack pattern, the sequence of attacks will change depending on how many tentacles are alive. Note that if Regenerator is cast at any point, the boss will start with the pattern for the amount of tentacles that are alive at that point, so it's important to keep track of how many tentacles are alive.

  • If 0 tentacles are alive: Fire > Ice > Volt > repeat
  • If 1 tentacle is alive: Ice > Volt > Fire > repeat
  • If 2 tentacles are alive: Volt > Fire > Ice > repeat
  • If 3 tentacles are alive: Fire > Volt > Ice > repeat
  • If 4 tentacles are alive: Volt > Ice > Fire > repeat
  • If 5 tentacles are alive: Ice > Fire > Volt > repeat
  • If 6 tentacles are alive: Volt > Fire > Ice > repeat
  • If 7 tentacles are alive: Ice > Volt > Fire > repeat
  • If 8 tentacles are alive: Fire > Ice > Volt > repeat

If you skipped killing the tentacles, the boss will a massive boost to its defensive power, being almost impossible to kill. Once you have defeated enough of them however, the fight becomes much more manageable. Regardless of how you proceed, the amount of tentacles left alive will have no effects on the second form, but since the fight has a time limit, you may want to defeat as many of them as possible. Once the creature's HP has been depleted, it'll move to the next phase of the fight.

Abyssal God
Abyssal god 2
A being that traversed space and time through an otherworldly sea. It awaits its awakening...
Enemy Data
HP 60000
ATK 87
DEF 71
EXP 300000
Skills Demon Rage, Chaos Tentacle, Rising Claw
Items Darkstar Bead
Weakness Elemental Attacks
Resistance None
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This is when the real fight begins. The Abyssal God is now capable of changing between two forms, its defensive form (mouth closed) and an offensive form (open mouth). The boss always starts this phase of the fight on its defensive form. The fight has 4 stages, with the fight becoming more erratic and random with each one of them.

Stage 1 (100-76% HP):

(Defensive Form)

While the boss is in this form, the Abyssal God will take lowered damage from all types of attacks. During this stage, it's best to buff your party and prepare whatever strategies you may have. The boss will use several counter skills through this stage in order to delay the fight. In this stage, it'll use its skills in the following order:

  1. Nameless Wall
  2. Mist Curtain
  3. Chaotic Beckon
  4. Spurting fumes
  5. Abyssal offering
  6. Form change + Demon Rage

Make sure none of your characters have low HP so no one dies from Chaotic Beacon, while this attack isn't very powerful, if you use skills similar Berserker Vow, some of your characters may be vulnerable to it. During this stage, it's not recommended to attack the Abyssal God, not only due to its massive defenses and possibly lethal counter-attacks but also the final cast of Abyssal Offering will likely heal any damage you deal to it. On the turn after the Abyssal God uses Abyssal Offering end its defensive stage, and the boss will change into its offensive form.

(Offensive Form)

The boss will open this form with Demon Rage. Once its mouth is open, the Abyssal God will lose its massive defensive power, but will also start using more powerful attacks. While on this form, the boss will use its attacks in the following order:

  1. Demon Rage
  2. Rising Claw
  3. Chaos Tentacle
  4. Primitive Burn
  5. Foul Glacier
  6. Dark Lightning
  7. Form change + Abyssal Offering

Since the boss' attack pattern is more predictable and its defense lower, strike this form with everything you have! While Demon Rage is a dangerous move, Rising Claw's damage is more manageable, and while Chaos Tentacle damage is lethal, you can easily block it with Overwatch. If you use a taunting move like Provoke or Daifuhensha while Bodyguarding the character with the taunt, (nearly) all the Demon Rage hits will go towards the guarding character. If you can block elemental damage with ease, the later half of this part form's pattern is a perfect opportunity to heal and go for an all-out attack!

If you fail do lower the Abyssal God's health beyond 75% before the 7th turn while in this form, it will change back to its defensive form, and restart the loop. Otherwise, once you deal enough damage to it, the Abyssal God will immediately change back to its defensive form, breaking its attack pattern and moving to the second stage of the fight.

Stage 2 (75-51% HP)

(Defensive Form)

Once the Abyssal God changes back to its defensive form, the fight becomes a lot more erratic. It will open this stage randomly using one of its counter attacks or using Chaotic Beckon, possibly recovering some of its lost HP. Its recommended not to attack on the turn the boss changes back, as the counter could end up dealing massive damage to your party. Keep an eye of the boss' HP bar, and once you think it's past 75%, cease all attacks against it.

From this stage on until the end of the fight, the Abyssal God will add a new mechanic to the fight in the form of a hidden count of how many it has acted on this form. Once said count has reached 6 actions, it will change forms, and every time it changes forms, the counter is reset to zero.

Each time the boss attacks or counter one of your attacks, the count increases by one. For example, if the boss activates Nameless Wall on its turn, that will count as one action. Additionally, each time said Nameless Wall counters one of you physical attacks, the action count will also increase by one.

That means that you'll want to trigger each of its counter-attacks as many times as you can per-turn, so that you can quickly go through the defensive form and return to the offensive one, allowing you to inflict damage to the boss again (remember, there's a time limit to the fight, you will not want to stagger it too much).

Additionally, the boss is aware of the kinds of attacks you use against it on that turn and will always use the proper counter attack. For example, if you use physical attacks against it on that turn, it will know to use Nameless Wall against you, and if you only use elemental attacks, it will always counter with Mist Curtain.

For that reason, dual wielding is extremely useful against this form, as your character will trigger multiple counters and quickly decrease the number of turns you will have to spend on this form.

One last mechanic to worry about is that, after its initial turn, if you do not attack the Abyssal God in this phase at all, it will instead of Nameless Wall or Mist Curtain use either Chaotic Beckon or, if you're unlucky, Abyssal Offering, potentially recovering a huge amount of HP and, if the HP % goes above 75%, going back to Stage 1 of the fight. As such it is important to always input at least one attack per turn to make sure it will cast a counterattack.

Once the action counter reaches 6, the boss will switch back to its offensive form.

(Offensive Form)

A new threat has also been added to the offensive form, as from here on out, the Abyssal God can freely change back to its defensive form at will. This is extremely dangerous, as the boss can now unleash powerful counters at you party at any possible moment. For this reason, while this is the perfect reason to go all-out on the boss, the longer you make the fight, the more you will be relying on luck to win it, make sure you don't make yourself too open for counters if you get unlucky and the boss changes form in the middle of your assault. Try avoiding multi-hit attacks and rather focus on single, powerful blows!

The boss will follow the following pattern while in this stage:

  1. Demon Rage
  2. Dark Lightning
  3. Foul Glacier
  4. Demon Rage
  5. Chaos Tentacle
  6. Rising Claw
  7. Form Change + Abyssal Offering

Stage 3 (50-26% HP)

(Defensive Form)

The boss will once again start this stage with either a random counter or Chaotic Beckon. This form's pattern works similarly to the previous one, but now it will prioritize the use of Spurting Fumes over other counter skills. For this reason, you might want to use the limit break Regroup Tactic, as it is an easy way to counter status effects. Again, make sure you get this form over as quickly as possible by triggering as many counters as you can afford to, and make sure you attack every turn to prevent the boss from healing itself. If you're confident you can finish the fight before turn 40, this is a good opportunity to heal and buff your party, as long as you have Regroup Tactic active.

Once again, 6 actions later, the boss will change to its offensive form.

(Offensive Form)

This time around, the boss will open this form's assault with either Primitive Burn, Foul Glacier or Dark Lightning, picked at random. Keep in mind that, if you've been relying on elemental prophecies to nullify the elemental damage from the boss, those skill will not work on the turn that the Abyssal God changes forms! If you want to block this first cast, you'll need to use the Hoplite's anti-elemental skills.

From now on, until its death, the Abyssal God no longer relies on attack patterns on its offensive form, and will attack you at random while in this stage. However, you can still predict what attacks are coming, to some extent:

  • If a party member is under the attack debuff from Primitive Burn, the attack will not be used.
  • If a party member has their head bound, the boss will not use Foul Glacier.
  • If a party member is being afflicted by sleep or confusion, Dark Lightining will not be used.
  • If a party member is below full health, Demon Rage will not be used.
  • If everyone is above 75% of their maximum HP, Chaos Tentacle will not be used.

That being said, which attack is used is still completely random. Each turn the boss will randomly choose between whatever attacks it has available or Rising Claw.

Stage 4 (24% HP to death)

(Defensive Form)

This time around, the Abyssal God will once again prioritize countering your attacks. Be aware however that unlike in Stage 2, it can still decide to randomly cast Chaotic Beckon, Spurting Fumes, or in the worst case, Abyssal Offering.

Once the action count reaches 6, it will become vulnerable again.

(Offensive Form)

Finally, the fight is at its final moments! No changes to this form of the fight - the boss will still use a random elemental attack as it changes back to its offensive form and follow the same logic as in Phase 3.

If at this point you reach turn 40, you might still have a chance to win if you somehow can withstand the boss' extremely powereful attacks while its berserking for a couple of turns while you finish the fight off. As the boss will no longer change to its defensive form, there will be no risks of random counters. Otherwise, you might want to reconsider your strategy and make adjustments to your party.

Skills Edit

First phase Edit

  • Magma Ocean (Uses Head): Deals heavy fire elemental damage to the entire party.
  • Ice Tempest (Uses Head): Deals heavy ice elemental damage to the entire party.
  • Proton Thunder (Uses Head): Deals heavy volt elemental damage to the entire party.
  • Regenerator (Uses Head): Revives a tentacle on the map, restoring 1000 HP to the Abyssal God, and increases its damage resistances.

Defense mode Edit

  • Nameless Wall (Uses None): Counters physical attacks with an almighty attack. The damage is proportional to how powerful the attack received was, meaning weaker attacks will receive less counter damage. If hit multiple times or by skills that lands several blows, this boss will unleash a counter for each time it has been damaged.
  • Mist Curtain (Uses None): Counters elemental attacks with an almighty attack. The damage is proportional to how powerful the attack received was, meaning weaker attacks will receive less counter damage. If hit multiple times or by skills that lands several blows, this boss will unleash a counter for each time it has been damaged.
  • Chaotic Beckon (Uses Legs): Moderate damage to the entire party. Restores some HP to the boss, proportional to the damage inflicted.
  • Spurting Fumes (Uses None): Counters all attacks by inflicting random status effects to the whole party. If hit multiple times or by skills that lands several blows, this boss will unleash a counter for each time it has been damaged. Can inflict petrify and a plague/poison status that deals 500 damage per turn.
  • Abyssal Offering (Uses Head): Removes all debuffs from the Abyssal God and recovers 11,475 to 11,480 HP from it.

Offense mode Edit

  • Demon Rage (Uses Legs): Hits 8 random targets, dealing heavy damage and removing their buffs.
  • Rising Claw (Uses Legs): Deals heavy slash damage to the whole party and may stun.
  • Chaos Tentacle (Uses Legs): Deals massive pierce damage to a single target. Always used on the character with lowest hp.
  • Primitive Burn (Uses Head): Deals heavy fire elemental damage to the entire party and inflicts a massive debuff to the targets' attack power.
  • Foul Glacier (Uses Head): Deals heavy ice elemental damage to the entire party and may inflict head bind.
  • Dark Lightning (Uses Head): Deals heavy volt elemental damage to the whole party and inflicts sleep or confusion.

Offense mode (past turn 40) Edit

  • Demon Rage (Uses Legs): Hits 2 random targets, dealing very heavy damage and removing their buffs.
  • Rising Claw (Uses Legs): Deals extremely heavy slash damage to the whole party and has a high chance to stun.
  • Chaos Tentacle (Uses Legs): Deals massive pierce damage to a single target. Now targets a random party member.
  • Primitive Burn (Uses Head): Deals very heavy fire elemental damage to the entire party and inflicts a massive debuff to the targets' attack power.
  • Foul Glacier (Uses Head): Deals very heavy ice elemental damage to the entire party and has a high chance to inflict head binds.
  • Dark Lightning (Uses Head): Deals very heavy volt elemental damage to the whole party and has a high chance to inflict sleep or confusion.

Drops Edit

  • Darkstar Bead (Worth: 100000 en)
  • None.

Conditional Drop Edit

  • None.



  • The Abyssal god and the entirety of the Cyclopean Haunt have numerous of references to the Cthulhu Mythos. In fact, it may be Cthulhu himself, taking into account the number of references and similarities:
    • The Cyclopean Haunt, where the Abyssal God is found, has several references to R'lyeh, where Cthulhu lies sleeping.
    • They are both worshiped by an aquatic species called the Deep Ones (Etrian | Lovecraft)
    • The B25F title, "That which can eternal lie". is a direct reference to a quote in one of H.P. Lovecraft's writings "That is not dead which can eternal lie", which refers to Cthulhu.
  • This is the first optional final boss of the series that got its own battle theme, as (Primevil used the standard boss battle music and Ur-Child used the Overlord's theme). This battle theme is called "Calling that Detestable Name".
  • This is the first boss fight in the DS series to have a fully animated background.
  • The Abyssal God is infamous for having an extremely difficult attack pattern to predict and its AI becoming more random and erratic as its HP lowers. Due to the poorly conveyed mechanics involved in the fight, and to how luck-based the battle can be, the Abyssal God stands as one of the most frustrating bosses in the series. This creates a stark contrast with the previous two superbosses in the series, Primevil and Ur-Child, who both have a more static and predictable AI, and makes the Abyssal God the first final superboss in the series to have a more dynamic fighting pattern.
  • Its first phase is somewhat similar to the Yggdrasil Core, which may hint at a similarity between the two.


Calling that Detestable Name

Calling that Detestable Name

Abyssal God's theme song

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