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Brain spiders were a rarely encountered species of spider-like creature with an unusual diet.[1] There was no known evidence of these creatures living in the Realms.[2][note 1]


The abdomen of these creatures resembled a gray, wrinkly mass of brain matter. Despite its appearance, this abdomen was in fact chitinous. And much like a true arachnid, its exoskeleton was supported by eight hairy legs that allowed it climb up walls and ceilings with ease. On the back of their four forelimbs were sharp points and jagged backhooks. On their heads were four eyes and a pair of powerful mandibles.[1]

On average their bodies, legs included, measured around 6 feet (1.8 meters) in diameter.[1]


Brain spiders were a semi-intelligent, though rather crude and stupid species. Cowards at heart, they would flee whenever one or more of their pack was slain. However, they displayed remarkable cunning when it came to hunting.[1]


Much like a true arachnid, brain spiders could inject their victims with venom, though they could not spin webs. Their venom attacked the central nervous system of those affected, traveling through nervous paths all the way to the brain. Paralyzing and then slowly killing them. When the venom's work is finished, a victim's nerves would be liquified.[1]

In addition, brain spiders possessed a number of psionic sciences and devotions, based around telepathy and psychometabolism, that they would utilize offensively. This included the following:[1]

body equilibrium, contact, double pain, ego whip, graft weapon, intellect fortress, mind blank, and shadow form.

Whenever they used graft weapon, items would be permanently grafted to them until they mentally rejected it. All items would received a +1 bonus. And any wands grafted to their bodies would be hooked into their nervous system.[1]


Brain spiders generally preferred to ambush their prey in groups. Dropping down from ceilings or other high ground or appearing from shadow form. When fighting creatures that lacked telepathy, they would coordinate with each other through that ability. They would focus their efforts on one or two victims, then flee and wait for their venom to do its work.[1]

Besides their venomous mandibles, brain spiders would rear up and attack prey with their hooked forelimbs. They often used their psionic ability graft weapon to bond objects, magical weapons, or wands to these limbs.[1]

Another one of their favorite tactics was to stand over some weak ledge, pit trap, or quicksand with their psionic ability body equilibrium and goad victims into trapping themselves. They also believed the ability double pain provided them particularly good sport.[1]


These creatures had a strict pack dominance hierarchy, would lower-ranked members being completely subservient to higher-ranked members. Their leaders were crude and brutish tyrants that were usually referred to by pompous titles, such as "King Venom" or "Master Thug."[1]

They often told each other tales of their most delicious kills, gruesome stalkings, and clever prey.[1]


Brain spiders fed upon the liquid nerves and brain matter of intelligent and psionic creatures. They were sometimes known to prey upon solitary drow and mindflayers.[1]


These creatures were only found underground, in areas with a subtropical climate.[1]


Brain spiders possessed their own unique language that was based around hissing.[1]


Brain spiders were known to act as servants of the deity Lloth.[2]



  1. There were no known instances of a brain spider in a Realms sourcebook. However, they are listed in Demihuman Deities as one of many creatures that could appear in the Realms to act on behalf of Loth. For this reason, brain spiders are documented in this article.


True Spiders
Natural spiders: BladeBloodwebBristleBudbackDaughter of LolthDireDoomspinnerGargantuanGee'aantuGiant (Giant FlyingGiant Water)Huge (DeathjumpWolf spiderWatchspider)IceRoaveSpittingSubterranean (FlyingHairySword)TarantulaVelsharess Orbb
Magical spiders: BloodsilkElectricGlassGazeGoblinPet of KalistesSpellgauntSteeder
Planar spiders: Demonweb terrorFireMyrlocharPhaseTombVortex

True Arachnids Considered Spiderkind

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