A hivemind consists of a swarm of smaller creatures whose individual minds have supernaturally bonded into one to become a single, collective intelligence. Hiveminds often occur in swarms that have existed for generations and that have dwelled in areas of potent magical influence, particularly areas of strong psychic magic. Over time, the swarm learns to work together in more intelligent ways to achieve its goals, and it eventually evolves a cohesive mind. of course, this evolution can be hastened by direct intervention of potent magic (typically something on the level of a miracle or wish), or as an unintended side effect of esoteric rituals, the use or destruction of artifacts, or the deaths of powerful minds.
A hivemind swarm learns from its surroundings, which in turn shape its choices in the languages it learns and the psychic spells it develops a penchant for casting. An urban swarm may pick up Common, Dwarven, Elven, or Halfling from snippets of conversations overheard through sewer grates, whereas an underground swarm may learn Dwarven or Undercommon. A hivemind may begin to exert its psychic abilities by compelling animals or people to bring it food or protect it from larger creatures, and it slowly graduates to defending itself and actively attacking as it gains experience.
Eventually, the hivemind’s mental network takes on more complex tasks as a collective mind. At this point, the hivemind creates a nexus, a single individual in the swarm through which the collective routes all thought. While the nexus is often fairly inconspicuous within the teeming mass of the swarm, it is possible for a highly perceptive observer to notice its decisive movements, spellcasting gestures, or intense gaze. The death of the nexus does not eliminate the shared intelligence of a hivemind, but it is disruptive, forcing the collective to focus inward to regroup and form a new nexus.
Creating a Hivemind Swarm
“Hivemind swarm” is an acquired or inherited template that can be added to any creature with the swarm subtype (referred to hereafter as the base creature). The hivemind template allows a swarm to increase in power and abilities, much like a class—when you create a hivemind swarm, you can customize its CR as needed by adjusting the number of additional Hit Dice (and thus associated statistics). A hivemind swarm uses the base creature’s statistics and special abilities except as noted here.
Senses: A hivemind swarm gains thoughtsense to a range of 60 feet.
Hit Dice: A hivemind swarm gains at least one racial Hit Die in addition to the Hit Dice of the base creature. The type of racial Hit Die the hivemind swarm gains is the same as that of the base creature. A hivemind swarm can never gain more than 20 racial Hit Dice in this manner.
Defensive Abilities: A hivemind creature retains all of the base creature’s defensive abilities and special qualities, including all swarm traits. Due to its increased Intelligence score, a hivemind swarm is not immune to mind-affecting effects; since a hivemind swarm has a single mind, mind-affecting effects treat it as a single target despite its numerous separate bodies.
Attacks: A hivemind creature retains its swarm attack, and continues to deal automatic damage to any creature whose space it occupies at the end of its move, with no attack roll needed. The swarm base damage is based on the hivemind’s Hit Dice, starting at 1d6 for 1 Hit Die and increasing by 1d6 for every additional 5 Hit Dice beyond the first.
Special Attacks: A hivemind creature retains all of the base creature’s special abilities and gains the following special ability.
Psychic Spellcasting (Su)
A hivemind creature gains the ability to cast psychic spells as per a psychic of a caster level equal to the number of additional Hit Dice it gains when it gains this template. A hivemind swarm can still deal swarm damage to creatures whose space it occupies at the end of its move, even if it has already cast a psychic spell in that round.
Ability Scores: If a base creature’s Intelligence score is 10 or lower, the hivemind swarm gains a base Intelligence score of 11. A hivemind swarm’s Intelligence score increases by 1 point for every Hit Die it gains beyond the base creature’s Hit Dice. If the base creature’s Charisma is lower than 10, the hivemind swarm gains a base Charisma score of 10. For every 4 Hit Dice the hivemind swarm gains beyond the base creature’s Hit Dice, it gains a +1 bonus to an ability score of its choice (this bonus can be applied to Intelligence, and it stacks with the bonus to Intelligence that a hivemind swarm gains for every Hit Die it attains).
Skills: A hivemind swarm loses all skill ranks that the base creature had but has skill ranks per racial Hit Die as defined by its creature type. A hivemind swarm’s class skills are the same as those that its creature type had and also include all Knowledge skills and Spellcraft.
Special Qualities: A hivemind gains the following.
Hivemind Nexus (Ex)
The collective intelligence of the hivemind comprises a complex series of connections and pathways among the members of the swarm. In order to focus the mental power of the swarm, the collective network of minds selects an individual member known as a “nexus.” It is through the nexus that all actions and decisions are routed to the entire hivemind. A hivemind nexus often acts in a slightly different manner than the other members of the swarm, and an observer can single out a hivemind swarm’s nexus as a move action with a successful Perception check opposed by the hivemind’s Bluff or Stealth check (whichever skill has a higher modifier for the hivemind). The hivemind gains a racial modifier of +10 on this Bluff or Stealth check, due to the hundreds of similar-looking creatures constantly moving around it. Once a nexus is spotted, it can be slain if the observer manages to deal at least 1 point of damage to the swarm, provided that damage is applied in the same round that the observer managed to identify the nexus. If a nexus is destroyed, the hivemind swarm is staggered and must succeed at a concentration check (DC = 15 + twice the spell level) in order to cast a spell. A hivemind swarm is able to create a new nexus by spending 1d6 rounds concentrating, during which time it can take no other action (including making any swarm attacks).
Pathfinder Roleplaying Game Bestiary 6 © 2017, Paizo Inc.; Authors: Robert Brookes, Benjamin Bruck, John Compton, Paris Crenshaw, Adam Daigle, Crystal Frasier, James Jacobs, Thurston Hillman, Tim Hitchcock, Brandon Hodge, Jason Keeley, Isabelle Lee, Jason Nelson, Tim Nightengale, F. Wesley Schneider, David Schwartz, Mark Seifter, Todd Stewart, Josh Vogt, and Linda Zayas-Palmer.