Creature Feature (5e): Powderbug Swarm

At first, powderbugs were heralded for their potential use as a black powder substitute. They required little food and harvesting them was a simple matter of leaving enough bugs for them to regrow their numbers. They bred voraciously. The initial batch was an expensive thing to produce, sure, but after that, the bugs were able to breed like any other living thing. Then came sabotage, either by natural accident or sapient interference. The bugs started swarming and growing aggressive. Worst, some batches began developing the ability to self-ignite, regardless of how ember free their environment. Woe to the first person who had to hear that now notorious powderbug click that signals their sparking. They never had a chance.

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Powderbug Swarm

Medium swarm of tiny monstrosities, unaligned

Armor Class 12 
Hit Points 30 (4d8 +12)
Speed 20 ft., climb 20 ft.

3 (-4) 10 (+0) 16 (+3) 1 (-5) 10 (+0) 2 (-5)

Damage Resistance Bludgeoning, Piercing, Slashing
Condition Immunities Charmed, Frightened, Paralyzed, Petrified, Prone, Restrained, Stunned
Senses passive Perception 10
Challenge 1 (200 XP)

Special Traits

  • Boom. A Powderbug Swarm immediately explodes in a chain detonation if dealt any fire damage whatsoever. In this scenario, the Powderbug Swarm immediately uses the Detonate action.
  • Swarm. The swarm can occupy another creature’s space and vice versa, and the swarm can move through any opening large enough for a Tiny insect. The swarm can’t regain hit points or gain temporary hit points.


  • Bites (swarm has more than half HP). Melee Weapon Attack: +2 to hit, reach 0 ft., one target in the swarm’s space. Hit: (4d4) piercing damage.
  • Bites (swarm has half HP or less). Melee Weapon Attack: +2 to hit, reach 0 ft., one target in the swarm’s space. Hit: (2d4) piercing damage.
  • Detonate. All creatures within 15 ft of the Powderbug Swarm (including those in a space it occupies) must make a DC 15 Dexterity save. On a failure, the creature takes 3d12 fire damage. On a success, a creature takes half. The Powderbug Swarm immediately dies. Powderbug Swarms only use take this action if forced to by fire damage through their Boom trait or if below 1/4 HP. 


Powderbugs are unnatural but generally are kept in relatively dark, damp environments to prevent accidental exposure to flame (for obvious safety reasons). Unfortunately, due to unforeseen issues with their breeding and development, they also tend to be ultra-aggressive in breeding season (usually late Summer) and when eating. For this reason, they are being kept less and less since less arcane methods of acquiring explosive powder are proving much more cost effective.

Enough powderbugs have escaped their enclosures to breed in uncontrolled environments that their behavior is important to note. These powderbug swarms tend to choose trees in relatively dry environments to make their homes. About the size individually as copper pennies, a single powderbug swarm actually eats far less than one might assume: despite feeding off local insect and plant life, individual swarms have a negligible impact on their environments. However, they breed rapidly and soon one swarm may grow too large, branching into two swarms. In a single year, one powderbug swarm can grow into as many as thirteen (1d12+1) if unchecked. These swarms have a 20% chance each year of getting into a conflict with another swarm, which almost invariably ends with both swarms exploding, causing sometimes massive fires in the dry environments they like to make their homes. 

Potential Uses

Powderbugs are the result of applying the arcane to modern industry. In effect, a team of dwarven scholars managed to produce a species of magical bug whose ground carapaces produce a powder nearly identical in properties to an equal measure of black powder. One powderbug swarm can produce enough gunpowder for 100 rounds of Powder & Shot, 50 Cartridges, or 25 Rifle Cartridges. Although additional materials must still be purchased to finish the ammunition these prices are largely negligible. It costs 8 gp per 100 rounds of Powder & Shot, 20 gp per 50 Cartridges, or 12 gp per 25 Rifle Cartridges produced in this way. 

Powderbugs are almost always drowned in order to harvest them. Drowning suppresses their ability to detonate and seems to suppress any remaining swarms and even bugs of the same swarm that survive’s ability to understand there was any kind of attack. Some experimentation with gas and cold have shown similar results if the swarm is killed before being injured enough to self-detonate.

A Rumor

Dozens of powderbug swarms have been released into the elven forest of Tarrendaal, threatening to completely devastate vital negotiations between the Tarrendaal elves and the dwarven Soothehammer clan that has taken residence nearby. The Soothehammer dwarves race to determine how their bugs were released, and reportedly suspect foul play. Meanwhile, the Tarrendaal elves view such claims merely as a smokescreen: the massive fires likely to soon spark will devastate their defenses and food supplies and prime them for a dwarven invasion, all while the dwarves can pretend their preemptive strike was merely an accident. 

About Quin Callahan

Quin Callahan is a freelance writer and college level English and economics tutor of over four years experience. He has written for a variety of gaming, technology, and economics publications. His favorite animal might be the squid but he is rarely certain.

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