Biting Gnat Swarm

Medium swarm of Tiny Beasts, unaligned

Armor Class 13
Hit Points 16 (3d8 + 3)
Speed 10 ft., climb 10 ft., fly 30 ft.

2 (–4) 17 (+3) 12 (+1) 1 (–5) 10 (+0) 1 (–5)

Damage Resistances bludgeoning, piercing, slashing
Condition Immunities charmed, frightened, grappled, paralyzed, petrified, prone, restrained, stunned
Senses passive Perception 10
Challenge 1/4 (50 XP)
Proficiency Bonus +2


  • Blood Sense. The biting gnat swarm can pinpoint, by scent, the location of warm-blooded creatures within 20 feet of it.
  • Distracting Buzz. A creature that is not deafened and starts its turn in a space occupied by a swarm of biting gnats must succeed on a Swarm of Biting Gnats DC 10 Wisdom saving throw or become distracted by the droning of the gnats’ wings. A distracted creature has disadvantage on attack rolls and ability checks that use Intelligence, Wisdom, or Charisma for 1 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, the creature is immune to the swarm’s Distracting Buzz for the next 10 minutes.
  • Swarm. The biting gnat swarm can occupy another creature’s space and vice versa, and the swarm can move through any opening large enough for a Tiny beast. The swarm can’t regain hp or gain temporary hp.


  • Bites. Melee Weapon Attack: +5 to hit, reach 0 ft., one target in the swarm’s space. Hit: 5 (2d4) piercing damage, or 2 (1d4) piercing damage if the swarm has half its hp or fewer. The target must succeed on a DC 11 Constitution saving throw or become blinded for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. Alternatively, the target can take an action to clear its eyes of the insects, ending the effect.


This cloud of flying insects is so densely packed it blocks all vision as it descends on its prey. While a single biting gnat may make itself a nuisance, easily swatted away or killed, clouds of the insects can nibble weaker victims to death.

Marsh Dwellers. Biting gnats thrive in damp environments and make themselves most at home in swamps, estuaries, and other wetlands. In areas with plenty of water and food, millions of gnats combine to create walls resembling storm clouds from a distance.

Denizens of locales hosting these insects who can withstand multitudinous gnat bites or can control the gnats use them as deterrents to intruders and spies. Because gnats primarily hunt warm-blooded creatures, an amphibious, reptilian, construct, or undead creature can pass through a swarm of gnats relatively unscathed.

Short Lifespans. Biting gnats live less than a week, discounting the many predators which feed on them. In that time, the carnivorous insects consume as much flesh and blood as possible and lay hundreds of eggs. By the time they die, they produce young in quantities up to double their original number.

Hardy Eggs. Swarms of biting gnats make surprise visits to areas with little rain since their eggs can enter dormancy for up to one year, spontaneously hatching and spreading during the first rain after a long drought. In areas where food is scarce, the insects seek out dry areas where their eggs can wait for better conditions.

Section 15: Copyright Notice

Tome of Beasts 3 © 2022 Open Design LLC; Authors: Eytan Bernstein, Celeste Conowitch, Benjamin L. Eastman, Robert Fairbanks, Scott Gable, Basheer Ghouse, Richard Green, Jeremy Hochhalter, Jeff Lee, Christopher Lockey, Sarah Madsen, Ben Mcfarland, Jonathan Miley, Kelly Pawlik, Sebastian Rombach, Chelsea Steverson, Brian Suskind, Mike Welham

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