The pursuit of epic power in Dungeons & Dragons is just one tether leading a potential magic user to their craft. For the Warlock, the source of that magic is a powerful patron who almost always has an agenda of their own. In exchange for their service to a patron, Warlocks can tap into a seemingly infinite source of power and magic -- but those rewards tend to come at a price.
Fathomless Patrons are colossal creatures from the darkest depths of the ocean, the Elemental Plane of Water, or some treacherous and unexplored sea. Whether those patrons reach out to find a pawn willing to carry out their plans to flood terrestrial planes and make way for their coming, or something far less sinister, accepting a pact with the Fathomless can be a treacherous path. Fortunately, there are specific stats, racial attributes, feats, and spells that grant this Warlock what they need to help them break free before it's too late, or, perhaps, even ride the wave of power into ultimate chaos and destruction.
Charisma Is the Fathomless Warlock's Core Stat
As a spell-caster, the Warlock is reliant on one specific core stat that powers their magical abilities: Charisma. CHA determines their spell casting modifier, damage bonus, and spell save DC. It also affects certain abilities, like how often they can summon the patron-specific tentacles granted from their Tentacles of the Deep feature. Additionally, CHA also boosts certain useful skills, like Intimidation, Persuasion, Performance, and Deception.
Almost equally important is the Warlock's Constitution score. CON influences a character's hit point pool and sustainability against debilitating effects like poisoning or exhaustion. As spellcasters, CON also bolsters their ability to maintain concentration for ongoing spell effects when they take distracting damage during combat.
The Best Races for the Fathomless Warlock
Choosing a race that offers a boost to CHA and/or CON is certainly a good option, and the Triton meets the requirements both physically and aesthetically. They get a +1 bonus to Charisma, Constitution, and Strength, and they actually come from the sea. On top of starting the game with the ability to breathe both air and water, they also have a pre-established walking and swimming speed of 30 feet. At level one, however, the Triton's natural swim speed increases to 40, making them even more efficient.
Because Tritons have adapted to the darkest depths of the oceans, they have immediate resistance to cold damage, a feature a Fathomless wouldn't receive from their patron until level six. They also have the ability to see in darkness, granting them darkvision for 60 feet. Tritons also have access to spells like Fog Cloud and Wall of Water, which aren't offered by their patron affiliation.
If playing an aquatic race feels too on the nose, Half-Elves are also a good choice. With a +2 boost to CHA, they also have two additional +1s they can tack on to other important abilities. The Mark of Storm variant is particularly good for a Fathomless Warlock, as they gain attributes from a house of seafarers, like Storm's Boon, which grants lightning resistance. They also have access to a unique list of spells that work hand in hand with those gained from their patron. Their Windwright's Intuition feature also provides an extra d4 that can be added to navigator's tools when making a Dexterity check to find their way.
Best Feats for the Fathomless Warlock
Because it's so important to get the Warlock's Charisma to 20 as quickly as possible, taking a feat can be a bit of a gamble. Look for feats that grant both useful abilities and a CHA boost. Fey Touched, for example, offers +1 CHA, and they gain access to Misty Step and one additional first level spell from the School of Divination or Enchantment. Shadow Touched also grants +1 to CHA, plus access to Invisibility and an extra first level spell from the School of Illusion or Necromancy.
It may also be prudent to consider the War Caster feat. This offers advantage on CON saves in order to maintain concentration on magical spells. The Warlock can also cast spells without using somatic components and make spell attacks when making an attack of opportunity.
Best Spells for the Fathomless Warlock
When choosing spells, consider how well those spells work for both aesthetic and damage. The cantrip Lightning Lure, for example, offers the ability to conduct electricity through the body and strike out at a target the Warlock can see within 15 feet. Armor of Agathys and Arms of Hadar are useful level one spells that seem as if they were specifically made for this subclass. Hunger of Hadar creates a horrifying void of fearful cacophony that doles out cold damage to anyone brave enough to start their turn in its sphere, and acid damage to those foolish enough to end their turn there.
As the Warlock gains levels, a spell like Maddening Darkness works very well to inflict the insanity of the darkest depths on unsuspecting victims, riddling them with psychic damage if they start their turn within the magical darkness. Because wind is just as much a part of the storms that stir the ocean, taking a spell like Investiture of Wind can improve the storms this Warlock rains bludgeoning damage down on enemies who dare to try and penetrate the swirling wind.
