There is a Legacy version
here.
Swarm Form
[two-actions] Focus 4Uncommon Cleric Concentrate Focus Manipulate Polymorph Source Divine Mysteries pg. 270Domain swarmDuration 5 minutes
You discorporate into a swarm of Tiny creatures. While in swarm form, you are the same size, you have the
swarm trait and you gain
resistance 5 to slashing and piercing damage and weakness 5 to area and
splash damage. You can fit into spaces only a few inches wide, moving your constituent creatures through the gap, and you can share a space with another creature. You don’t gain the
swarm mind ability, so you are still affected normally by mental effects. As a swarm, you can’t speak,
cast spells, use
manipulate actions requiring your hands,
activate your magic items, or make any of your
Strikes with your normal body. While in swarm form, you can crawl all over any creature that shares your space as a single action. That creature must attempt a Fortitude save against your spell DC or become
sickened 1 (sickened 2 on a critical failure). You can
Dismiss the Spell.
Heightened (+2) Your resistances and weaknesses each increase by 5.