Swarmform CollarEquipment 7
Source Pathfinder Lost Omens: The Grand Bazaar
Price 350 gp
Weight 1 bulk
This sturdy leather collar is imprinted with tessellated animal shapes. When invested, the animal shapes change to match that of your companion.
Activate 
envision, Interact
Frequency once per day
Effect You touch the collar and your companion splits into a swarm of hundreds of identical Tiny versions of itself for 1 minute. Its space becomes Large, it gains the weaknesses and resistances of a Spider Swarm, and the swarm trait, though it doesn't gain swarm mind, as it's controlled by a single mind. Its unarmed attacks are replaced with a single-action swarming attack that deals 1d8 damage of the type normally inflicted by the companion's unarmed attacks to any foe in its space, with a DC 23 basic reflex save. While in swarm form, your companion can take the Support action but can't perform its advanced maneuver. Its other statistics don't change. If the companion is reduced to 0 Hit Points while in swarm form, the companion immediately recombines into its original form in an available space, in addition to the usual effects of being reduced to 0 Hit Points.
Traits
Something of uncommon rarity requires special training or comes from a particular culture or part of the world. Some character choices give access to uncommon options, and the GM can choose to allow access for anyone. Less is known about uncommon creatures than common creatures. They typically can't be summoned. The DC of Recall Knowledge checks related to these creature is increased by 2.
CompanionAn item with this trait can be worn by an animal companion or similar creature. A companion can have up to two items invested.
InvestedA character can wear only 10 magical items that have the invested trait. None of the magical effects of the item apply if the character hasn't invested it, nor can it be activated, though the character still gains any normal benefits from wearing the physical item (like a hat keeping rain off their head).
PrimalThis magic comes from the primal tradition, connecting to the natural world and instinct. Anything with this trait is magical.
TransmutationEffects and magic items with this trait are associated with the transmutation school of magic, typically changing something's form.