Fathomless Warlock Guide for Beginners: Mastering the Abyssal Depths in D&D 5e

The Fathomless Warlock is a spellcaster who has formed a pact with a powerful entity from the deep sea, such as a kraken, an ancient leviathan, or an eldritch sea god. Introduced in Tasha’s Cauldron of Everything, this subclass is perfect for players who want to wield the power of the ocean, summon spectral tentacles, and control the battlefield with aquatic magic.

Unlike other Warlocks, Fathomless Warlocks excel at battlefield control, summoning abilities, and environmental adaptability, making them one of the best crowd-control and mobility-focused Warlock subclasses in D&D 5e. If you love the idea of commanding the tides, grappling enemies with eldritch tentacles, and exploring the depths of the unknown, this subclass is for you!

Why Play a Fathomless Warlock?

Key Benefits

• Best Warlock for Battlefield Control – Use spectral tentacles to slow, damage, and restrict enemy movement.
• Summonable Tentacles for Extra Damage – Bonus action control that works every turn.
• Excellent Utility & Exploration Abilities – Swim faster, breathe underwater, and teleport through water.
• Excels in Both Offense & Defense – Increase survivability while maintaining strong spellcasting.
• Perfect for Nautical Campaigns & Lovecraftian Horror Themes – Thematic synergy with deep-sea adventures and eldritch horrors.

Compared to other Warlocks, Fathomless Warlocks provide the best balance of crowd control, mobility, and consistent damage.

Core Features

Key Mechanics and Abilities

Expanded Spell List (Fathomless Patron Bonus Spells)

• Gain access to spells focused on water, storm, and battlefield manipulation:
  • Create or Destroy Water, Thunderwave (3rd)
  • Gust of Wind, Hold Person (5th)
  • Lightning Bolt, Sleet Storm (9th)
  • Control Water, Summon Elemental (Water) (13th)
  • Cone of Cold, Bigby’s Hand (reskinned as a spectral tentacle) (17th)
• Example: Cast Lightning Bolt for powerful ranged damage or Hold Person to lock down foes.

Tentacle of the Deeps (Level 1)

• As a bonus action, summon a spectral tentacle within 60 feet.
• Tentacle lasts for 1 minute and can:
  • Strike an enemy, dealing cold damage and reducing their speed by 10 feet.
  • Make additional attacks each turn.
• Example: Summon a spectral kraken tentacle to slap enemies while restricting their movement!

Gift of the Sea (Level 1)

• Gain a swimming speed of 40 feet and breathe underwater.
• Example: Explore deep oceans, cross rivers easily, and fight effectively underwater.

Oceanic Soul (Level 6)

• Resistance to cold damage.
• Communicate telepathically with creatures swimming near you.
• Example: Negate frost-based attacks and communicate with aquatic creatures.

Guardian Coil (Level 6)

• Your Tentacle of the Deeps can now protect allies:
  • When an ally within 10 feet of the tentacle is attacked, reduce the damage they take by 1d8.
• Example: Position your tentacle strategically to defend squishy allies.

Grasping Tentacles (Level 10)

• Automatically learn Evard’s Black Tentacles (doesn’t count against spells known).
• You can cast it once per long rest without using a spell slot.
• Gain temporary HP equal to your Warlock level when casting it.
• Example: Trap multiple enemies with massive writhing tendrils and gain bonus HP for extra survivability.

Fathomless Plunge (Level 14)

• Teleport yourself and up to five willing creatures within 1 mile of a body of water you’ve seen.
• Works through oceans, lakes, rivers, or even small puddles!
• Example: Escape deadly fights or ambush enemies from an unexpected location!

These abilities make Fathomless Warlocks some of the best at battlefield control, providing constant utility, area denial, and defensive bonuses.

Suggested Ability Scores

• Primary: Charisma – Powers spellcasting and eldritch abilities.
• Secondary: Dexterity – Improves AC and initiative for quick reactions.
• Tertiary: Constitution – Helps with survivability and Concentration saves.

Recommended Races

Since Fathomless Warlocks rely on Charisma, Dexterity, and survivability, the best races include:

1. Triton – Perfect thematic choice, with water magic and cold resistance.
2. Water Genasi – Breathes underwater and resists acid damage.
3. Sea Elf – Great mobility in water and natural weapon proficiency.
4. Half-Elf – Charisma boost and extra skill proficiencies.
5. Variant Human – Start with a feat like War Caster or Telekinetic.

Playing as a Fathomless Warlock

Role in a Party

• Primary Battlefield Controller & Defender – Summon tentacles to restrict movement and reduce damage taken.
• Strong Utility & Exploration Warlock – Survive and navigate in water-based environments.
• High Mobility & Defensive Capabilities – Teleport through water, reduce damage, and reposition strategically.

Compared to other Warlocks, Fathomless Warlocks provide some of the best area control and environmental adaptability, making them incredibly useful in both combat and exploration.

Tips for New Players

• Always summon your Tentacle of the Deeps early – It’s a free damage dealer and battlefield controller.
• Grasping Tentacles is a game-changer – Trap enemies and gain free temporary HP.
• Fathomless Plunge is great for team mobility – Escape danger or initiate fights from an unexpected angle.
• Guardian Coil is perfect for protecting allies – Place your tentacle in key locations to reduce incoming damage.

Gear and Dice Recommendations

Suggested Equipment

Weapons & Arcane Focus

• Rod of the Pact Keeper – Boosts Warlock spells and regains a spell slot.
• Wand of the Depths – Enhances water-based magic.

Armor & Defensive Items

• Cloak of the Manta Ray – Grants excellent underwater movement.
• Ring of Free Action – Ignore difficult terrain and paralysis effects.

Magic Items

• Pearl of Power – Recover a spell slot in emergencies.
• Trident of Fish Command – Thematic and useful for commanding sea creatures.
• Amulet of the Depths – Grants water breathing and resistance to cold.

Dice Recommendations from Runic Dice

Enhance your oceanic and storm-themed adventures with these exquisite dice sets:

• Abyssal Tide Dice Set: For deep blues and greens representing the endless ocean depths, consider the Labradorite Gemstone DND Dice Set. Handcrafted from genuine labradorite, these dice exhibit a mesmerizing play of deep blue and green hues, capturing the mysterious allure of the abyss.
• Kraken’s Wrath Dice Set: To embody eldritch sea power with dark purples and blacks, the Purple Gemstone Amethyst DND Dice Set is an excellent choice. Made from genuine amethyst, these dice showcase rich purple tones, reflecting the formidable presence of the legendary kraken.
• Stormcaller Dice Set: For blue and silver tones representing tempestuous sea magic, the Blue Sandstone Silver Font Gemstone DND Dice Set offers deep blue hues with shimmering silver inclusions, symbolizing the raw energy of a raging storm.

Advanced Tips and Tricks

Optimization Strategies

Best Feats for a Fathomless Warlock

1. Telekinetic – Enhance battlefield control with forced movement.
2. Metamagic Adept – Gain Quickened or Distant Spell for better control.
3. War Caster – Maintain Concentration on key spells.
4. Resilient (Constitution) – Boosts Concentration saves.
5. Lucky – Reroll crucial attack rolls, ability checks, or saving throws.

The Fathomless Warlock is one of the most adaptable, battlefield-controlling, and exploration-friendly subclasses in D&D 5e, excelling at tentacle-based combat, area denial, and underwater mobility.