Starfinder: Thinker Arachnid

Chris Van Deelen

Thinker Arachnid Expert CR 8 XP 4,800

Neutral huge vermin

Init +0; Senses: Darkvision 60 ft.; Perception +21


Defense                                                             HP 115

EAC: 20; KAC: 21

Fort: +9; Ref: +7; Will: +13

Defensive Abilities: DR 4 / -, Hardened survivor; Immunities: Fire, poison, radiation



Speed: 10 ft.

Melee: Probe +17 (1d12+10 P)

Space: 15 ft., Reach: 5 ft.

Offensive Abilities: Mental blast, psionic spike



Str +2; Dex +0; Con +0; Int +6; Wis +4; Cha +0

Skills: Bluff +16, intimidate +21, life science +16, physical science +16, sense motive +21

Feats: Iron will

Other Abilities: Bolster the swarm, fear aura, telepathic communication

Languages: Telepathy



Environment: Any

Organization: Solitary


Special Abilities

Bolster the Swarm (Su): This psychic ability allows the Thinkerto improve the will saves of all the Arachnids within a 200 foot range of the creature by +4, and it also removes any mental conditions such as stunned, shaken, and so on. This is a full round action and the creature must concentrate each round to maintain it. If the concentration fails, the Arachnids in the area of effect will revert to their usual Will save. The thinker can maintain this indefinitely, as long as it can concentrate, but it can only be used once per day once it has dropped the bolster effect.

Fear Aura (Su): The Thinker generates a aura of absolute terror. Other Arachnids are immune to the effect, but non-arachnids must make a Will save (DC 18) or become shaken for 1d6 rounds. This is a constant ability and can be supressed by the Thinker if it so desires.

Hardened Survivor (Ex): The Thinker is completely immune to poisons and radiation, and it is able to withstand extreme conditions, even utter vacuum. Whenever the beast must make a saving Fortitude saving throw when dealing with environmental conditions, it gains a +10.

Mental Blast (Su): When the Thinker is in danger; it can release a powerful psychic blast. This will affect any non-Arachnid within 75 feet. Those who are in this area are allowed a Will save (DC 18) or be hit by the blast. They suffer 4d4+8 points of damage and are staggered. A successful save negates the effects. This is a standard action and the creature can use this once every three rounds.

Psionic Spike (Su): As a standard action, the creature is able to directly attack a single target with a powerful jolt of psionic energy which bypasses any type of damage reduction. The victim is allowed a Will save (DC 18) or they will suffer 2d6+8 points of damage, and suffer 1d4 points of temporary wisdom damage. A successful save halves the damage and no will is lost. This is a standard action and the creature can use this once every second round.

Telepathic Communication (Ex): The Thinker is able to telepathically speak with any creature within its line of sight. This bypasses the need to be able to speak or understand any language. This can be used at will.


The thinker is the commander of the Arachnid army. They command all the Arachnids they have and are able to co-ordinate their movements and are in constant mental communication with all.

The Thinker is a massive, slug-like monstrosity which is 15 feet in length, 10 feet in height, and easily weighs in at over 5000 pounds. It moves slowly and ponderously on small legs situated on the bottom of the creature.

Situated at the front of the beasts body is the creature’s head. It has two rows of four eyes on either side of the slit-like mouth, and a pair of small appendages which can be used to manipulate or hold. A long folding tongue will push out from the slit and it has an incredibly sharp spike at the end. The Thinker can use this to penetrate the skull of a victim, killing and sucking the brains out of the poor creature. All knowledge the victim had at the time of death is absorbed by the Thinker and it can use this knowledge to create missions and attack plans, which is distributes to the Arachnids under its control.

Because of the Thinker’s importance to the swarm, it is always protected by no less than 8 warriors and often has other Arachnids nearby to act as protectors and guardians. It is not uncommon for Tanks to be nearby as well, and thanks to the fact the Thinker is immune to the napalm-like flame they use, it will often allow them to spray the flame over it if the Thinker is being overrun by the enemy.

It is very possible to communicate with the Thinker, although it tends to be set on its goal, and will typically only accept any sort of communication that will benefit It and the rest of its swarm. It is difficult to bluff or intimidate the creature, and usually when it debases itself to communicate with lesser beings, it is to demand their unconditional surrender.

As this is the literal brain of the swarm, capturing or killing the Thinker will throw the Arachnids under its control into panic and mayhem. The creatures will wander aimlessly, stand still and not react, even when attacked, or in the case of the warriors, they will attack everyone and everything in sight – including other Arachnids, until they are destroyed or a new Thinker arrives on scene to take control of the swarm.

I would like to give a special shout-out to Lloyd Calvin for helping me with this work! Thanks bud!

Starfinder Creature Index

Chris Van Deelen is the creator and contributor to over half of the Wisdom from the Wastelands series, contributor to the Swords of Kos: Hekaton anthology, and the recently released 'Swords of Kos: The Rite'. He also wrote Creatures of the Tropical Wastelands, and 100 Oddities found in a Car. As prolific as he is, Chris Van Deelen continues to write and produce material which will be in publication soon. Not only is he a prolific content creator, he also has a wide selection of fiction and stories! If you like his work, please follow his personal author page on Facebook and on Twitter to keep up with his latest news and game content.