The ocean is a realm of both beauty and terror. Gentle giants like whales can inspire awe in a swimmer, while the denizens of the deepest depths might cause one’s skin to crawl. Warlocks attracted to this diverse selection of beings should look toward the Fathomless subclass, which is offered in Tasha's Cauldron of Everything.

This patron can take on a myriad of forms, ranging from a godly dragon turtle to a tentacled monstrosity with an unpronounceable name, venerated by kuo-toa cultists! Click below to learn more:

• The Fathomless features
• Pros
• Cons
• Sample build

The Fathomless features

Expanded Spell List

Warlocks who choose the Fathomless gain access to spells largely related to water or the thunderous storms of the ocean. Among these, thunderwave, gust of wind, sleet storm, and control water are all useful options for taking control of the battlefield. Lightning bolt and cone of cold are excellent offensive spells, while summon elemental can come in handy if your party needs a water elemental to soak up damage. Bigby’s hand, which manifests as a Large tentacle instead of a hand, is a fun choice that leans into this subclass’ aquatic theme.

Tentacle of the Deeps

At 1st level, the Fathomless warlock can summon a 10-foot-long spectral tentacle at any point within 60 feet. The tentacle lasts for 1 minute and can be summoned a number of times equal to the warlock’s proficiency bonus, with all expended uses regained after a long rest. Upon creating the tentacle, warlocks can make a melee attack against a creature within 10 feet, dealing 1d8 cold damage on a successful hit and reducing the foe’s speed by 10 feet until the start of the warlock’s next turn. Warlocks can use their bonus action to move the tentacle up to 30 feet and repeat the attack. Upon reaching 10th level, the tentacle’s damage bumps up to 2d8.

Though Tentacle of the Deeps lacks the damage scaling of a cleric’s spiritual weapon, it’s almost a near-copy otherwise, and makes up for its decreased damage with a 10 foot range. Since the summoned tentacle is spectral and cannot be targeted by enemies, this makes it a go-to ability in a fight.

Gift of the Sea

Another 1st level feature, Gift of the Sea gives the warlock a swimming speed of 40 feet and the ability to breathe underwater. It’s only appropriate that a subclass relying so heavily upon the ocean should offer underwater breathing, and considering that even tritons only have a base swimming speed of 30 feet, Gift of the Sea is a good boost.

Oceanic Soul

This 6th level ability confers resistance to cold damage, which is always welcome. But more interestingly, Oceanic Soul enables the warlock to understand the speech of any creature as long as both parties are submerged. This reminds me of the 1989 sci-fi film The Abyss, where a group of submarine operators attempt to communicate with a watery alien. It would also allow a Fathomless warlock to chat up all manner of sea life a la Aquaman.

Since this ability specifies that both parties simply need to be submerged in order to understand each other, it also opens up ridiculous roleplay possibilities. What if the warlock is trying to interrogate a drow who only speaks Undercommon? They might not be able to understand each other, but if there’s a pool nearby, all they need to do is take a dive! (On that note, while the Fathomless warlock can breathe underwater, there’s no guarantee that the other creature can, so care should be taken to avoid unintentionally drowning someone!)

Guardian Coil

This 6th level feature modifies Tentacle of the Deeps. Now, the tentacle can defend both the warlock as well as any other creature within 10 feet of it that takes damage. Activating this ability requires a reaction, and the warlock can select their target and choose to reduce the damage to that creature by 1d8. Upon reaching 10th level, the damage reduced by the tentacle increases to 2d8.

Tentacle of the Deeps is already a solid ability, but Guardian Coil makes it even better, especially for a group of adventurers fighting in close quarters with enemies surrounding them. The image of a massive, see-through tentacle surrounding all members of a party and deflecting projectiles is an evocative one, to say the least.

Grasping Tentacles

At 10th level, the warlock learns the spell Evard’s black tentacles, which does not count against the number of spells they know. The spell can be cast once without using a spell slot, and the warlock regains the ability to do so after a long rest. The warlock also gains a number of temporary hit points equal to their level whenever they cast the spell, and damage cannot break their concentration. Like many of the options on this subclass’s expanded spell list, Grasping Tentacles offers up the handy ability to control the battlefield while dealing damage and keeping the warlock’s hit points high.

Fathomless Plunge

At 14th level, the warlock can use an action to teleport themself and up to five other willing creatures within 30 feet to any body of water within 1 mile that they’ve seen. The body of water has to be the size of a pond or larger, and the warlock can also choose to have the teleported creatures appear within 30 feet of it.

This feature, which can only be used once per short or long rest, can be useful during an emergency situation where the party is outnumbered, outclassed, or simply in need of a quick respite. But it’s also heavily situational, and if there aren’t any decent bodies of water within a mile, the Fathomless warlock is out of luck.

Pros

The Fathomless warlock was made for those who love the idea of pledging their character to a kraken or an otherworldly entity like Olhydra, Princess of Evil Water. For those players, as well as anyone looking to excel in a seafaring campaign like Ghosts of Saltmarsh, the Fathomless is an easy choice. Warlocks less sold on the concept can look forward to great flexibility if they select this patron, with a tentacle that lets them deal damage and protect allies, and a variety of spells that will make them the mover and shaker of any battlefield.

Cons

Like the Circle of Wildfire druid, another subclass centered around a particular element, the Fathomless warlock’s features can be neutered depending on the campaign. A Fathomless warlock in a desert campaign might be hilarious but suffer mechanically. Many of this subclass’ expanded spells also deal cold, thunder, or lighting damage, and will be less effective in a campaign featuring enemies resistant or immune to these damage types.

Finally, Fathomless Plunge is an underwhelming 14th level ability, especially when compared to its Unearthed Arcana incarnation, which let the warlock choose between teleporting or manifesting part of their patron into reality for 6d10 cold or lightning damage.

Meet Vemre, sailor of the Astral Plane and the Elemental Plane of Water

The gith cheered as the last mind flayer fell, heaping praise and adoration upon their captain, the great Vemre — wielder of magical tentacles from the elemental planes. They cheered even louder as Vemre stepped to the forecastle of the ship, carrying a deceased illithid's body. With one swift sword strike, the githyanki cleaved the tentacled aberration's head open. The Sha’sal Khou captain manifested a spectral tentacle and latched onto the illithid's brain, removing it with a loud squelch.

"Don't grimace," she said as the cheers turned to disgust, "they would've done the same to us with nary a second thought. And besides, I have an unusual friend to feed."

Vemre is a member of the Sha’sal Khou, the organization that seeks to unite the two splintered factions of the gith race: the githyanki and githzerai. Trained to wield both blade and magic as a githyanki gish, Vemre served on the Sha’sal Khou astral ship Liberation, and spent years sailing the Astral Plane on diplomatic expeditions and occasionally more violent missions to exterminate illithids, the enslavers of all gith.

On one such mission, Vemre and her crewmates found themselves fighting illithids who had magical artifacts at their disposal, including a cubic gate. In the midst of a terrific battle, Vemre fell through a portal created by the cubic gate, landing in a forgotten region of the Elemental Plane of Water. There, she began to drown, but a mysterious voice entered her mind and asked if she wanted a second chance at life. Vemre agreed, and at that moment, gained the ability to breathe underwater.

Her savior was Sbinxulgu, a rotund and surprisingly benevolent aboleth who enjoyed existence as a local deity amongst select marids. Sbinxulgu added that it was a connoisseur of interplanar cuisines, and appeared to be oddly familiar with the Astral Plane, hinting that it had once been banished from traveling there. The aboleth said that it knew of a planar portal that could take Vemre back home, and even offered to bless the githyanki with other incredible gifts. In exchange, Sbinxulgu asked that Vemre returns on a monthly basis with two delicacies that were hard to come by on the Elemental Plane of Water: astral whale flesh and mind flayer brains.

Baffled by the feeding habits of her savior but bolstered by the thought of having yet another reason to kill illithids, Vemre accepted and returned home to her people with a strange story and even stranger magic at her disposal. Vemre is now captain of the Liberation, and also leads Sha’sal Khou outpost missions along the Sword Coast. A master at sailing both star oceans and regular oceans, Vemre lives to unite her people, vanquish mind flayers, and collect the peculiar cuisines that her portly patron requires.

Playing Vemre

Vemre is a chaotic neutral githyanki with the Sailor background. She has a high Charisma score and a good Constitution score. Her Dexterity, Intelligence, and Wisdom scores are lower but still above average. She has proficiency in the following skills and tools:

• Athletics
• History
• Intimidation
• Perception
• Cartographer's Tools
• Navigator’s Tools
• Vehicles (Water)

Vemre’s connection with the Elemental Plane of Water and Sbinxulgu has given her the ability to understand Deep Speech, which incidentally also happens to be the language of mind flayers. She also has the War Caster feat and makes full use of the expanded Fathomless Warlock spell list. Her go-to spells in a pinch also include the likes of eldritch blast and lightning lure, and she can cast mage hand, jump, and misty step due to her githyanki heritage.

In ship battles, Vemre will launch into the fray with Sbinxulgu’s tentacles and use spells like gust of wind and sleet storm to knock opponents overboard. She also has the Mystic Arcanum spell investiture of ice, which supplements grasping tentacles and makes it difficult for foes to reach her without taking damage.

During her travels, Vemre has taken great care to map out hundreds of secret portals to and from the Elemental Plane of Water. If a crisis is imminent, she will not hesitate to use Fathomless Plunge to teleport companions to one of these portals if it is within range. If it is not, she will cast plane shift, which also allows for an easy return to the Astral Plane. If for whatever reason neither of those options are available, Vemre has recovered the cubic gate that initially united her with Sbinxulgu, and carries it with her at all times.

Playing Vemre as an NPC

Vemre can be a powerful ally to any group of high-level adventurers about to embark on interplanar travel, and she will immediately take a liking to heroes sympathetic to the Sha’sal Khou cause. Sbinxulgu can be a fun NPC for a group of players too accustomed to the idea that aboleths must be evil, and was vaguely inspired by Beerus, a deity in the Dragonball Super anime who wields destructive power but has an amusing love for earthly cuisine.

Summon the sea to your side

For players in love with the ocean and all of its creatures both gentle and frightening, the Fathomless is the perfect patron. With the power of the sea in their pocket, Fathomless warlocks can wield a unique combination of defensive and offensive powers as flexible as the ebb and flow of the tides, bringing thalassic might across the planes of existence.

Fizban's Treasury of Dragons releases October 19 and will be packed with dragon lore and stat blocks for new kinds of dragons. Players will enjoy new subclasses and dragonborn ancestries and more! You can preorder your copy now on D&D Beyond. If you have a Master-tier subscription, you can share your book and other content you've unlocked in the marketplace with players in your campaigns.

Jeremy Blum (@PixelGrotto) is a journalist, gaming blogger, comic book aficionado, and fan of all forms of storytelling who rolled his first polyhedral dice while living in Hong Kong in 2017. Since then, he's never looked back and loves roleplaying games for the chance to tell the tales that have been swirling in his head since childhood.