Brain in a Jar

Family: Clockwork

Small undead, neutral evil

Armor Class 15 (mage armor)
Hit Points 77 (14d8 + 14)
Speed 0 ft., fly 20 ft.

1 (-5) 15 (+2) 13 (+1) 18 (+4) 16 (+3) 19 (+4)

Skills Arcana +8, Deception +8, Insight +6, Persuasion +8
Damage Resistances psychic
Damage Immunities poison
Condition Immunities poisoned
Senses darkvision 60 ft., passive Perception 13
Languages Common, Deep Speech, telepathy 100 ft.
Challenge 5 (1,800 XP)



  • Telekinetic Projectile. Ranged Weapon Attack: +8 to hit, range 120 ft., one target. Hit: 11 (2d6 + 4) bludgeoning, piercing, or slashing damage. The brain in a jar hurls a nearby object at the target; the type of damage depends on what the object is (GM’s discretion).
  • Psychic Strike. Ranged Spell Attack: +8 to hit, range 60 ft., one target. Hit: The brain in a jar can choose one of the following effects, with the target allowed a DC 16 Wisdom saving throw.
    • Ego Whip: The target cannot take bonus actions or reactions and has disadvantage on Intelligence and Charisma checks and saving throws for 1 minute if it fails its saving throw, or 1 round on a successful save. The target can attempt a new saving throw each round at the end of its turn to end the effect.
    • Id Insinuation: The target is confused (as a confusion) spell for 1 minute. The target can attempt a new saving throw each round at the end of its turn to end the effect.
    • Inflict Pain: The target is treated as if poisoned for 1 minute on a failed save or has disadvantage on attack rolls for 1 round on a success. The target can attempt a new saving throw each round at the end of its turn to end the effect; disadvantage from the poisoned condition does not affect this saving throw. This affects living creatures immune to poison but has no effect on creatures immune to psychic damage or immune to being charmed or frightened.
    • Mental Block: The target’s access to its trained skills and memories is lost for 1 round on a failed saving throw. Each round thereafter at the beginning of its turn, the target can attempt a new saving throw. The effect ends on a success; if failed, the effect persists for 1 more round (maximum 1 minute). While affected by the mental block, the target’s its proficiency bonus is reduced to 0 for all purposes other than saving throws and it cannot use feats or cast spells or activate magic items or use other magical abilities.
    • Mind Thrust: The target takes 22 (5d8) psychic damage, or half as much on a successful save.
  • Unliving Master (Recharge after Long Rest). The brain in a jar can command up to 14 Hit Dice of undead creatures or constructs within 30 feet, though none can have more than 7 Hit Dice. These creatures can resist its control with a DC 16 Wisdom saving throw. If failed, they are charmed by the brain in a jar for 7 days. Creatures with Intelligence 5 or greater can attempt a new saving throw after 24 hours and every 24 hours thereafter to end this effect. The brain in a jar can attempt to control new undead or constructs; if it succeeds and this would bring the total Hit Dice of controlled creatures over 14, it can end the charm for one or more previously controlled creatures to bring the total to 14 or less. Creatures the brain in a jar controls are connected to it by a telepathic bond, even if their Intelligence is 2 or lower.


These vile creatures are hideous mental monstrosities preserved beyond death in exotic alchemical solutions in containers of glass and crystal, with eldritch energies giving animation and awareness to deceased cerebral tissue. Their mental powers are considerable, though their physical remains are scarcely able to move encased as they are within their jars. Their minds retain considerable psychic potency, building on any they possessed in life but also unlocking psychic potential that may have gone untapped in their mortal years. The process is highly traumatic in any event, the stress leaving the creature’s mental matrix fractured, hateful, and unstable. They work through minions whenever possible but lash out with telepathic and telekinetic fury when their plans are thwarted.

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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