Entity: Swarm

Source Battlecry! pg. 72

Your eidolon is a collective of primal energy and nature spirits, gathered into a single fragmentary being. This collection of natural energy has neither form nor identity until bonded with a summoner. You give these spirits purpose, connecting with them and drawing them through to the physical realm. When manifesting, these nature spirits don a simple form, adopting the guise of many Tiny animals. Each of these animals is the same creature and is marked with your summoner’s sigil. The act of manifesting in this swarm form temporarily binds the spirits together into one being, making the eidolon a single entity—one mind and personality speaking with a multitude of voices, and a multitude of bodies acting in concert with a singular purpose.

Your eidolon is an intelligent swarm composed of hundreds of Tiny creatures, and it’s immune to the grabbed, prone, and restrained conditions. It can fit through tight spaces as though it were a Tiny creature. It has weakness to area damage equal to its level. Your eidolon has two forms: condensed and dispersed. When you Manifest Eidolon, it manifests condensed. It can switch between these two forms as a single action that has the concentrate trait.

Condensed Form: When condensed, your eidolon draws all its component bodies into a single, condensed mound that functions as a Medium creature. It has a reach of 5 feet, can make Strikes, and can’t occupy the same space as other creatures. While condensed, it can use the Haunting Visage action.

Dispersed Form: When dispersed, your eidolon scatters its component bodies across a wider area, increasing its size by one category (to Large for most swarm eidolons). It has a reach of 0 feet, can’t make Strikes, and can occupy the same space as other creatures. While dispersed, it can use the Swarming Assault activity.