Swarm of Miniature Mermaids

Family: Swarm

Large swarm of Small humanoids (merfolk), neutral

Armor Class 13
Hit Points 60 (11d10)
Speed 10 ft., swim 40 ft.

12 (+1) 16 (+3) 10 (+0) 8 (–1) 14 (+2) 17 (+3)

Skills Perception +4
Damage Resistances bludgeoning, piercing, slashing
Condition Immunities charmed, frightened, grappled, paralyzed, petrified, prone, restrained, stunned
Senses passive Perception 14
Languages Aquan, Common
Challenge 3 (700 XP)


  • Amphibious. The swarm can breathe air and water.
  • Smothering Embrace. While in water, a creature in the swarm’s space is at risk of suffocating. It must succeed on a DC 13 Constitution saving throw to hold its breath or begin choking. A choking creature can survive a number of rounds equal to its Constitution modifier (minimum of one round) before dropping to 0 hit points and dying.
  • Swarm. The swarm can occupy another creature’s space and vice versa, and the swarm can move through any opening large enough for a Small mermaid. The swarm can’t regain hit points or gain temporary hit points.


  • Bites. Melee Weapon Attack: +5 to hit, reach 0 ft., one creature in the swarm’s space. Hit: 21 (6d6) piercing damage, or 10 (3d6) piercing damage if the swarm has half its initial hit points or fewer.
  • Haunting Melody (recharge 6). The voices of the dozens of miniature mermaids harmonize into a haunting melody. Each creature within 30 feet of the swarm that can hear it must succeed on a DC 13 Charisma saving throw or be charmed by the swarm for one minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature’s saving throw is successful or the effect ends for it, the creature is immune to the swarm’s Haunting Melody for the next 24 hours.


Colorful fish swam in lazy circles. There was even a shark! I remember seeing something small swim toward the glass, then another, and another. I was amazed. Mermaids! Tiny mermaids! I remember them singing such a beautiful melody. — Holy warrior Jurgen DeFetterlind, found wandering the Haunted Steppes while dragging the bodies of his four friends in a net Miniature mermaid swarms consist of tiny mermaids that swim together like a school of fish. They raise their voices together in a song that can charm anyone they encounter. They swarm prey that enters their watery depths, drowning them.

Section 15: Copyright Notice

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

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