Corrosive Slime
CREATURE 3A corrosive slime can sense nearby creatures through vibration and air or water movement.
When the Corrosive Slime moves, it leaves a trail of bubbling slime in its wake. After moving, all squares the Corrosive Slime moves from or through count as Difficult Terrain until the end of the corrosive slime's next turn. Creatures which end their turn in one of those squares must succeed at a DC 20 basic Reflex save or take 2d8 acid damage.
1d6 bludgeoning plus 1d6 acid, DC 20 basic Fortitude
The monster deals the listed amount of damage to any number of creatures Grabbed or Restrained by it. Each of those creatures can attempt a basic Fortitude save with the listed DC.
The monster can instead use Grab and choose one creature it's grabbing or restraining with an appendage that has Grab to automatically extend that condition to the end of the monster's next turn.