Mass Wriggle⟲Trigger The rat snake swarm takes damage from a melee Strike
Effect Snakes slither up and around the creature's weapon and limbs. The target must succeed at a DC 15 Will save or become Frightened 1.
Speed
20 feet, climb 20 feet, swim 20 feet
Swarming Strikes◆ Each enemy in the swarm's space takes 1d8 piercing damage (DC 17 basic Reflex save).
Source: Pathfinder Monster Core 2
Running this fight? Add the rat snake swarm to the initiative tracker: type its name and the AC, hit points and Perception for initiative fill in, and the book button shows this stat block mid-fight.