Large swarm of Tiny constructs (robot, nanite), unaligned

Armor Class 15
Hit Points 162 (17d10 + 68)
Speed 10 ft., fly 20 ft. (hover)

1 (-5) 18 (+4) 19 (+4) 14 (+2) 17 (+3) 3 (-4)

Skills Perception +8
Damage Resistances bludgeoning, piercing, and slashing
Damage Immunities necrotic, poison, psychic
Condition Immunities charmed, frightened, grappled, paralyzed, petrified, prone, restrained, stunned
Senses blindsight 60 ft., passive Perception 18
Languages Common but can only communicate directly with other machines, including androids without special equipment
Challenge 7 (2,900 XP)


  • Blessing of the Iron Gale. The malfunctioning nanite swarm performs one of the following changes to a target before moving on to another target. You can roll randomly or pick an appropriate effect. The swarm does not attempt to kill its target; however, its modifications may cause the target to die anyway. This smaller manifestation of the storm only affects living creatures – constructs, such as robots and androids are immune to this secondary effect. A creature can resist the effects on a successful DC 15 Constitution saving throw. On a roll of a natural 1 the shock to the system is so great that the creature dies minutes after the effect takes place.
  • Baleful Transformation. The storm changes the subject into a beast with a Challenge of no greater than one-third the target’s actual level and/or Challenge (such as a dog, lizard, monkey, spider, toad etc.). The subject takes on all the statistics and special abilities of an average member of the new form in place of its own. The transformation is imperfect – the creature is always a chimera of some kind mixing multiple creature traits though these are usually superficial.
  • Cloud. The storm 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 throw. Creatures that are not swarms are distracted by the surging wave of constructs 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.
  • Mutation. The creature is mutated somehow. The GM must decide exactly how and if it is beneficial or not, superficial or not etc.
  • Weakness. When the storm damages a living creature, it disrupts the transmission of nerve impulses to the creature’s muscles, causing weakness. Mechanically this is represented by a permanent poisoned condition.


  • Nanite Storm. All creatures sharing a space with the swarm or within 5 feet of it automatically take 25 (5d10) piercing and necrotic damage (evenly split between the two), or 15 (3d10) piercing and necrotic damage if the swarm has half of its hit points or fewer. The target must also make a DC 15 Constitution saving throw or be exposed to the Blessing of the Iron Gale trait.


  • Reconstructive Healing. As a reaction, a nanite storm can heal a single living target it shares a space with, healing 6 (2d6) points of damage. The cloud often triggers this ability when it reduces a creature to 0 hit points, so as to stabilize the target. The cloud can administer this healing in an instant before resolving any actual damage dealt to prevent a creature’s death from its attacks.


Appearing as a shimmering and sometimes colorful curtain of light an auto-minima storm is more a natural disaster in numbers than a monster to be defeated. Better to be avoided than confronted.

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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