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Huge monstrosity, lawful evil

Armor Class 16 (natural armor)
Hit Points 266 (28d12 + 84)
Speed 0 ft., swim 20 ft.

14 (+2) 10 (+0) 16 (+3) 19 (+4) 17 (+3) 18 (+4)

Saving Throws Int +11, Wis +8
Skills Intimidation +14, Perception +13, Persuasion +14
Senses blindsight 120 ft., passive Perception 23
Languages Aquan, telepathy 120 feet
Challenge 16 (15,000 XP)


  • Oceanic Domination. A deepmind exercises psychic control over all sea creatures that have an Intelligence score of 2 or less within a one-mile radius. Creatures of Intelligence 3 or higher must make DC 18 Intelligence saving throws or are also controlled. If actively resisting control, creatures of Intelligence 3 or higher can make a saving throw at the end of each of their turns to break the control. A creature that succeeds on its saving throw is immune to that deepmind’s control for 24 hours. Controlled creatures obey the deepmind’s commands. The deepmind can also see and hear through its controlled creatures, which allows it to make Wisdom (Perception) checks through their senses. Controlled creatures also act to defend the deepmind if so commanded. Creatures that are not native to the ocean — such as humans, elves, or dwarves who are underwater through magical means — are immune to the deepmind’s control.


  • Multiattack. The deepmind makes six Tentacle attacks.
  • Tentacle. Melee Weapon Attack: +9 to hit, reach 50 ft., one creature. Hit: The target is grappled (escape DC 15). Until the grapple ends, the target is restrained and has disadvantage on Strength checks and Strength saving throws, and the deepmind can’t use the same tentacle on another target. While grappled, the target takes 12 (3d6 + 2) bludgeoning damage at the beginning of the deepmind’s turn.
  • Psychic Pulse (recharge 5–6). The deepmind unleashes a pulse of pure psychic energy over a 50-foot radius centered on itself. Any living creature in the area except those controlled by the deepmind through its Oceanic Domination ability must make a DC 18 Wisdom saving throw, taking 66 (12d10) psychic damage and being stunned until the start of the deepmind’s next turn on a failed save, or half as much damage and not being stunned on a successful saving throw.


The alien jellyfish creatures known as deepminds dwell in the depths of the sea, often in ocean trenches, unaffected by the massive pressures there. Highly hostile and dangerous, deepminds control all of the unintelligent sea life in surrounding regions, using them for defense against intruders and other deepminds.

The deepmind floats in the cold darkness of the ocean depths, illuminated by a faint bluish glow. Several small tentacles hang from its central mass, while six larger ones ring the body, gleaming with tiny eyespots. They reproduce asexually by budding. Young deepminds have their full powers within a matter of days and strike out instinctively, seeking out new territories to dominate. While they are solitary and extremely hostile creatures, deepminds are highly intelligent and can communicate mentally and in the Aquan language. They are driven by self-interest and the need to survive and accordingly are willing to make deals with other intelligent sea creatures, especially those of evil alignment. Such allies reward a deepmind by keeping outsiders away while using sea creatures dominated by the deepmind for their own purposes.

Section 15: Copyright Notice

Tome of Horrors 2020, (C) 2020, Necromancer Games

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