Brain Cylinder (Scholar)

Brain cylinders are alien technology, originating with the fungi from Yuggoth. They are used to preserve intact the brains of other organisms so that the fungi can carry them into space or other worlds. The fluid within the cylinder has a faint glow, and particles of light can be seen “crawling” up and down the brain and brain stem. Unless the brain is of unusual size, the cylinder containing it is not particularly large—only a foot or two long at most and half as wide.

Cylinders need not be transparent and can be made from any substance, including metals or other materials that are typically used in forging armor. The fungi themselves tend to make the main part of the cylinder out of armored glass, which is difficult but not impossible to pierce.

Brain cylinders properly stocked with the mi-go’s glowing fluid never run out of energy: they can keep a brain alive and well for centuries. The extradimensional fluid taps into other planes of existence for its power.

Cylinder Attachments

The cylinder has a number of plugs for attaching devices to it, which enable the brain to see, hear, and communicate, as well as perform other functions (see sensory machines starting on page 128). The fungi have a huge variety of devices they have created for the cylinders, including means of interrogation and even torture.

The devices that plug into the cylinder can easily be modified from magic items built for humanoid races, and the cylinder itself is made from normal terrestrial substances. Cylinders can even be constructed by skilled human craftsmen. The true alien technology is not the cylinder itself but the liquid in which the brain floats. This substance is partially extra-dimensional (as are the fungi themselves) and has a sort of life of its own.

Bodiless Immortality. The transparent fluid constantly repairs and maintains the healthy state of the brain, preventing deterioration. It even cures existing ailments, averts new ones, and effectively grants the brain immortality. While in the vat, the brain needs no food, water, or air, although it must still sleep.

Construct Controllers. The fungi can plug brain cylinders into bio-mechanical constructs and use them to control work machines or other large and complex devices. These constructs are rare outside of the fungi home-worlds since they are heavy and often quite large, making them difficult to transport.

BrainCylinder Template

An aberration, beast, giant, humanoid, monstrosity, or undead can become a brain cylinder if it has a brain. It keeps its statistics, except as follows.

Challenge. In most cases, the creature loses all means of defending itself, reducing its challenge rating to 0 (0 XP). If the creature retains some means of attack, its challenge rating must be recalculated. Most often, such a creature’s challenge rating is reduced by 1.

Size. The brain cylinder’s size is three steps smaller, to a minimum of Tiny.

Type. The brain cylinder’s type is construct.

Armor Class. The brain cylinder’s AC becomes 18 from its armored glass casing.

Hit Points. The brain cylinder’s Hit Dice are reduced to suit its new size, but if it has fewer than 5 Hit Dice, it gains Hit Dice until it has 5.

Speed. The brain cylinder is immobile. It loses all special speeds and its base speed is 0 feet.

Ability Scores. The brain cylinder’s Strength and Dexterity scores are 0.

Damage Resistances. The brain cylinder gains resistance to acid, fire, lightning, and poison damage. It also gains resistance to bludgeoning, piercing, and slashing damage from nonmagical attacks that aren’t adamantine.

Damage Immunities. The brain cylinder gains immunity to cold damage.

Senses. The brain cylinder loses all special senses and is blinded and deafened unless it has appropriate sensory machines attached.

Languages. The brain cylinder can’t speak unless it has a proper sensory machine attached.

Traits. The brain cylinder loses all traits that rely on its previous physical body.

New Trait: Immobile. The brain cylinder can’t move or speak without external assistance, giving it an effective speed of 0, and it can’t benefit from any bonus to its speed. Without assistance, it automatically fails Strength and Dexterity saving throws, and it can’t take actions or reactions that require any bodily movement.

If the brain cylinder can cast spells, it must have a speech sensory machine attached to provide verbal components and it must have a vision sensory machine attached to aim spells that require it to choose a target or point it can see. It can’t provide material components unless it is attached to a drone or the material components are touching it.

Actions. The brain cylinder has no physical means of attack. It loses all attacks and other actions that rely on its previous physical body, including most attacks other than ranged spell attacks.