Ooze, Assembly

Medium ooze, unaligned

Armor Class 13
Hit Points 8 (1d8+4)
Speed 30 ft.

14 (+2) 12 (+1) 18 (+4) 1 (-5) 6 (-2) 2 (-4)

Damage Vulnerabilities lightning
Condition Immunities blinded, charmed, deafened, exhaustion, frightened, prone
Senses blindsight 60 ft., passive Perception 8
Languages understands the languages of its creator but can’t speak
Challenge 1/8 (25 XP)


  • Assemble. Assembly oozes can shape raw materials and manipulate parts to create finished products. They can also disassemble existing mundane items to obtain raw materials. Given access to materials, the ooze will create random arms, armor, tools and adventuring equipment until the materials run out.


  • Disassemble. Melee Weapon Attack: +4 to hit, 5 ft. reach, one target. Hit: 4 (1d6 + 1) acid damage.


Thought to have been created as a biotechnological replacement for automation processes, assembly oozes are essentially cores of nanobots suspended within blobs of animated protoplasm. As the ooze absorbs raw materials, the nanobots work at the molecular level to turn that matter into a functioning technological device, the blueprints of which have been entered into the machines’ original programming.

An assembly ooze resembles a human-sized, silvery cube, though its amorphous form allows it to slip through incredibly small openings. As it moves, surging forward on its pseudopods, random scraps the ooze has already collected sometimes float near the creature’s surface before quickly disappearing into its form. Entirely focused on absorbing and reshaping any available technology, assembly oozes usually ignore organic matter, living or otherwise, unless threatened. However, should a creature have mechanical or cybernetic elements attached to or incorporated into its physical form, an assembly ooze could very well cause that creature incidental harm in its attempts to harvest the technological parts. Sentient robots are extremely wary of assembly oozes, as their entire bodies could be targeted for processing into raw resources.

Corrupted Technology. Due to sloppy programming procedures, the code embedded within an assembly ooze has an unfortunate tendency to easily become corrupted, causing the ooze to haphazardly deconstruct any nearby tech and use the pieces to build random items. The first time this occurred, several assembly oozes escaped the ensuing purge and built copies of themselves, eventually spreading to various shadowy corners of the galaxy.

While these rogue oozes are not all that dangerous and have no innate malice, they are the bane of space stations, starships, weapon depots, and anywhere else technology is present. When discovered in such a location, assembly oozes are ruthlessly exterminated, lest their nonstop disassembling of all things mechanical and electronic destroy critical systems—to say nothing of the new, potentially lethal devices left in their wake. While assembly oozes are still used in some factories and its more toxic moons, their use is highly regulated.

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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