Nanobot Mimic Swarm

Family: Nanobot

Medium swarm of Tiny constructs (robot, shapechanger, technological), unaligned

Armor Class 11
Hit Points 52 (8d8 + 16)
Speed 30 ft., fly 30 ft.

12 (+1) 13 (+1) 14 (+2) 6 (-2) 10 (+0) 9 (-1)

Damage Resistances bludgeoning, piercing, slashing
Condition Immunities charmed, frightened, grappled, paralyzed, petrified, prone, restrained, stunned
Senses darkvision 60 ft., passive Perception 10
Languages Common
Challenge 4 (1,100 XP)


  • Electrical Weakness. The swarm has disadvantage on saving throws against lightning damage. If it rolls a natural 1 on the save it is stunned until the end of its next turn.
  • Metal Morass. The swarm surrounds foes it shares a space with, making it hard for them to escape. A creature that starts its turn in the same space as the swarm must succeed at a DC 11 Dexterity saving throw or become restrained until the end of their turn.
  • 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 construct. The swarm can’t regain hit points or gain temporary hit points. A swarm takes half damage from attacks that use an attack roll and double damage from effects that require it to make a saving roll. Creatures that are not swarms are impaired while they remain in the swarm’s space or within 5 feet of it and have disadvantage on attack rolls and Constitution saving throws to maintain concentration. The area of the swarm is considered difficult terrain.


  • Swarm of Needles. The swarm attacks all creatures that share a space with it and automatically does 22 (6d6 + 1) necrotic damage, or 11 (3d6 + 1) necrotic damage if the swarm has half of its hit points or fewer, and the target also takes 1 necrotic damage at the start of its turn until it makes a DC 12 Constitution saving throw. This necrotic damage is accumulative and persists even after leaving the swarm’s space. A healing spell automatically removes any accumulated necrotic damage after the target leaves the swarm or the swarm is destroyed.
  • Mimic Fixture. The swarm can polymorph into an object or back into its true, amorphous cloud form. Its statistics are the same in each form except while in object form it has a damage threshold of 5. If attacked, it may use its reaction to revert into its swarm form and take its turn in combat. It reverts to its true form if it dies.


  • Thirsting Flight. When an enemy in the swarm moves away from it, the swarm may use its reaction to move up to its speed to the triggering enemies’ space (or as a close as possible). This movement does not provoke attacks of opportunity.


Rumored to be the invention of a malicious roboticist, nanobot mimics take the appearance of technological objects, using the deception to launch surprise attacks. Each mimic is a swarm of nanobots that interlock to imitate an item. When a would-be looter picks up the nanobot mimic, the construct dissolves into a dark and silvery cloud of its component nanobots. These then swarm the victim, hindering and attempting to disassemble it.

Illegal Machines. Nanobot mimics are often quasi-legal. They see some licensed use as security. However, criminals use these constructs far more often, since they serve as fine traps for investigators. Clever scofflaws make mimics look like illegal objects to draw attention. When a detective noses into an area and finds the mimic, the creature not only attacks and makes the target more vulnerable to other attacks but can also dispose of the body.

Section 15: Copyright Notice

Mechanical Monsters (5E) © 2023, Legendary Games; Authors: Jason Nelson, Miguel Colon, Robert J. Grady, Nicholas Hite, Matt Kimmel, Michael Mifsud, James-Levi Cooke, Dan Dillon, Mike Myler, Ismael Alvarez, Jeff Lee, John Lynch.

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