Medium construct, neutral

Armor Class 17 (natural armor)
Hit Points 90 (12d8 +36)
Speed 40 ft.

17 (+3) 16 (+3) 17 (+3) 3 (-4) 14 (+2) 3 (-4)

Skills Perception +5
Damage Vulnerabilities acid
Damage Resistances bludgeoning, piercing, and slashing damage from nonmagical attacks
Damage Immunities necrotic, poison, psychic
Condition Immunities charmed, exhaustion, frightened, paralyzed, poisoned
Senses darkvision 120 ft.; passive Perception 15
Languages understands commands given in Undercommon but can’t speak
Challenge 6 (2,300 XP)


  • Charging Trample. If the mechanasphere moves at least 20 feet straight toward a target and then hits with a rolling slam attack on the same turn, the target suffers an additional 10 (3d6) bludgeoning damage. If the target is a creature, it must succeed on a DC 14 Strength saving throw or be forced prone.
  • Magic Resistance. The mechanasphere has advantage on saving throws against spells and other magical effects.
  • Magic Weapons. The mechanasphere’s weapon attacks are magical.


  • Multiattack. The mechanasphere makes two attacks with its whirling blades or one attack with its whirling blades and one rolling slam.
  • Scything Blades. Melee Weapon Attack: +6 to hit, reach 5 ft., one creature. Hit: 7 (1d8 + 3) slashing damage.
  • Tolling Slam. Melee Weapon Attack: +6 to hit, reach 5 ft., one creature. Hit: 10 (2d6 + 3) bludgeoning damage.
  • Whirling Blades (Recharge 5-6). The mechanasphere can use its action to spin its blades in a series of interweaving arcs, targeting creatures of its choice within 10 feet of it in any direction. Each target must make a DC 14 Dexterity saving throw, taking 21 (4d8 + 3) slashing damage on a failed save or half as much damage on a successful one.


  • Initial Round-The mechanasphere attacks the creature nearest to the construct’s assigned area, often using its Charging Trample to force intruders back to knock them off-balance.
  • Subsequent Round(s)-In later rounds, the construct uses the threat of its trample, or its Whirling Blades attack to drive enemies into nearby traps, pits, and similar obstacles.
  • Defensive Round-The mechanasphere has no concern for its own safety. If it senses it has sustained serious damage, it does everything in its power to kill as many intruders as quickly as possible.
  • Victorious Round-When all intruders are dead, the mechanasphere returns to its guard post and awaits either additional intruders or new orders from its controller.
  • Defeat Round-If a mechanasphere has been defeated, the victors can salvage one of these valuable components from the intact wreckage. See the Mechanasphere Components table for details.


A mechanasphere is a powerful construct employed by duergar to defend their holy shrines and protect their secrets from intruders (and to a duergar, everything represents a secret). This construct, fashioned from brass and iron and powered by magically-infused crystal shards, obeys its master’s commands without question for centuries.

Then first encountered, the mechanasphere is likely in its dormant mode, resembling a metallic lattice globe with internal clockwork gear mechanisms. When activated by the presence of intruders, this globe spins to extend a set of three curved blades as well as a blocky mechanical head with glowing red eyes. The duergar jealously guard the secrets to the construction of mechanaspheres. Building one of these constructs demands a considerable outlay in coin, time, and effort. It also requires rare gemstones, precious metals, and magical crystal shards to power the machine.

A mechanasphere remains intact, functional, and alert for centuries, hyper-vigilantly guarding its assigned location to

d6 Mechanasphere Components
1 A silver strut worth 75 gp.
2 A small brass cog worth 100 gp.
3 A large brass cog worth 150 gp.
4 A pair of rubies worth 150 gp apiece.
5 A collection of tiny metallic gears and small precious gemstones worth 300 gp.
6 A vial of oil of slipperiness-d3 applications.
Section 15: Copyright Notice

Book of Monstrous Might (C) 2021 Total Party Kill Games. Author(s): Brian Berg, Mark A. Hart & Danny Grimes.

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