Collective Knowledge

Swarm. The swarm can occupy another creature's space and vice versa, and the swarm can move through any opening large enough for a Tiny object. The swarm can't regain hit points or gain temporary hit points.

Fireproof Volumes. The books comprising the swarm are protected by a magical enchantment that makes them immune to fire damage.

Non-Sentient Objects. The individual books are ordinary, non-sentient objects. Their animation and coordination are entirely the result of the enchantment binding them together.

Bound to the Library. The swarm cannot willingly leave the library. Any books separated from the library's boundaries cease to function as part of the creature and become ordinary, inanimate books.

Distributed Existence. Collective Knowledge consists of multiple independent swarms. Destroying one swarm does not destroy the others. The creature is only completely destroyed when every active swarm has been reduced to 0 hit points.

Shared Initiative. All active swarms of Collective Knowledge share the same initiative count. Each swarm takes its own turn independently, with its own movement, action, bonus action, and reaction. The DM chooses the order in which the swarms act when they share an initiative count.

Mass-Based Damage. The swarm's damage is determined by its current hit points. For every 10 current hit points, it deals an additional 1d3 damage. A swarm with fewer than 10 current hit points still deals 1d3 damage as long as it has at least 1 hit point.

Mass-Based Reach. The swarm's melee reach is determined by its current hit points. Its reach is 5 feet, increasing by 5 feet for every 50 current hit points it has. This progression has no maximum.

Book Swarm. Melee Weapon Attack: +7 to hit, reach determined by Mass-Based Reach, one target. Hit: 1d3 bludgeoning damage for every 10 current hit points the swarm has (minimum 1d3). The swarm deals bludgeoning damage as hundreds of books strike, batter, and crush the target.

Overwhelm. One Large or smaller creature within the swarm's reach must succeed on a DC 15 Strength saving throw or become grappled and restrained by the swarm. While restrained in this way, the creature takes 1d3 bludgeoning damage for every 10 current hit points the swarm has (minimum 1d3) at the start of each of the swarm's turns. The creature can use its action to repeat the saving throw, escaping on a success.

Volumetric Barrage. The swarm launches a portion of itself at a point it can see within 60 feet. The swarm chooses how much of its mass to commit, in increments of 10 maximum hit points. The committed portion must have sufficient current hit points available.

Creatures in a 15-foot cube centred on the chosen point must make a DC 16 Dexterity saving throw, taking 1d3 bludgeoning damage for every 10 hit points committed on a failed save, or half as much damage on a successful one.

After the attack, the committed portion arrives at the chosen point and becomes a separate swarm with current and maximum hit points equal to the amount committed. The original swarm loses the corresponding amount of current and maximum hit points.

Divide. The swarm separates a portion of itself in increments of 10 maximum hit points. It must retain at least 10 maximum hit points and have sufficient current hit points to commit the chosen amount.

The newly separated swarm has current and maximum hit points equal to the amount committed. The original swarm loses the same amount of current and maximum hit points.

Each resulting swarm is an independent creature for all combat purposes, including movement, actions, bonus actions, reactions, targeting, and damage. All swarms share the same initiative count.

Recombine. The swarm merges with another swarm of Collective Knowledge that has fewer maximum hit points than itself. The contributing swarm disappears, and the receiving swarm gains maximum hit points equal to the contributor's maximum hit points. The receiving swarm also regains current hit points equal to that amount, up to its new maximum hit points.

A swarm cannot Divide and Recombine during the same turn.

Minimum Swarm Size. A swarm must have at least 10 maximum hit points. It cannot divide itself into a portion smaller than this amount. A swarm reduced below 10 current hit points remains active until reduced to 0 hit points.