Voidworm

Entropy Sense (Imprecise) 30 feet (divine, prediction) — A voidworm can anticipate the most likely presence of a creature through a supernatural insight into chaotic probabilities and chance. This grants them the ability to sense creatures within the listed range. Veil of Privacy prevents a creature from being detected via entropy sense automatically (without a counteract check).

Constant Spells — A constant spell affects the monster without the monster needing to cast it, and its duration is unlimited. If a constant spell gets counteracted, the monster can reactivate it by spending the normal spellcasting actions the spell requires.

Fast Healing 1 — A monster with this ability regains the given number of Hit Points each round at the beginning of its turn.

Protean Anatomy 5 (divine) — A voidworm's vital organs shift and change shape and position constantly. Immediately after the voidworm takes acid, electricity, or sonic damage, they gains the listed amount of resistance to that damage type. This lasts for 1 hour or until the next time the voidworm takes damage of one of the other types (in which case its resistance changes to match that type), whichever comes first.

The voidworm is immune to polymorph effects unless it is a willing target. If Blinded or Deafened, the voidworm automatically recovers at the end of its next turn as new sensory organs grow to replace the compromised ones.

Change Shape (concentrate, divine, polymorph) — The voidworm takes on the appearance of a Tiny animal. This doesn't change their Speed or their attack and damage bonuses with their Strikes but might change the damage type their Strikes deal.

The monster changes its shape indefinitely. It can use this action again to return to its natural shape or adopt a new shape. Unless otherwise noted, a monster cannot use Change Shape to appear as a specific individual. Using Change Shape counts as creating a disguise for the Impersonate use of Deception. The monster's transformation automatically defeats Perception DCs to determine whether the creature is a member of the ancestry or creature type into which it transformed, and it gains a +4 status bonus to its Deception DC to prevent others from seeing through its disguise. Change Shape abilities specify what shapes the monster can adopt. The monster doesn't gain any special abilities of the new shape, only its physical form. For example, in each shape, it replaces its normal Speeds and Strikes, and might potentially change its senses or size. Any changes are listed in its stat block.

Confounding Lash (divine, emotion, mental) — A creature hit by the voidworm's tail Strike is Stupefied 1 for 1 round (Stupefied 2 on a critical hit). A successful DC 16 Will save negates this effect and grants temporary immunity to confounding lash for 1 minute.