Hollow Serpent

Lifesense 60 feet — Lifesense allows a monster to sense the vital essence of living and undead creatures within the listed range. The sense can distinguish between the vitality energy animating living creatures and the void energy animating undead creatures, much as sight distinguishes colors.

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.

Desiccation Aura (aura, divine) — 30 feet. A cloud of choking, acrid dust swirls about the hollow serpent, draining moisture from any enemy within. A creature entering the aura or starting its turn in the aura must succeed at a DC 34 Fortitude save or become Enfeebled 2 and Slowed 1 for 1d4 rounds (2d4 rounds on a critical failure). A creature that succeeds is temporarily immune for 24 hours.

Divine Guardian —

Void Healing — A creature with void healing draws health from void energy rather than vitality energy. It is damaged by vitality damage and is not healed by vitality healing effects. It does not take void damage, and it is healed by void effects that heal undead.

Constrict — 1d10+7 bludgeoning plus Drained 1, DC 36 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.

Slithering Strike — The hollow serpent Strides or Climbs and makes a jaws Strike at the end of that movement. If the hollow serpent began this action Hidden, it remains hidden until after this ability's Strike.

Swallow Whole (attack) — Medium, 4d6 void plus Drained 1, Rupture 32

The monster attempts to swallow a creature of the listed size or smaller that it has grabbed or restrained in its jaws or mouth. If a swallowed creature is of the maximum size listed, the monster can't use Swallow Whole again. If the creature is smaller than the maximum, the monster can usually swallow more creatures; the GM determines the maximum. The monster attempts an Athletics check opposed by the grabbed creature's Reflex DC. If it succeeds, it swallows the creature. The monster's mouth or jaws no longer grab a creature it has swallowed, so the monster is free to use them to Strike or Grab once again. The monster can't attack creatures it has swallowed.

A swallowed creature is Grabbed, is Slowed 1, and has to hold its breath or start suffocating. The swallowed creature takes the listed amount of damage when first swallowed and at the end of each of its turns while it's swallowed. If the victim Escapes this ability's grabbed condition, it exits through the monster's mouth. This frees any other creature grabbed in the monster's mouth or jaws. A swallowed creature can attack the monster that has swallowed it, but only with unarmed attacks or with weapons of light Bulk or less. The swallowing creature is Off-Guard against the attack. If the monster takes piercing or slashing damage equaling or exceeding the listed Rupture value from a single attack or spell, the swallowed creature cuts itself free. A creature that gets free by either Escaping or cutting itself free can immediately breathe and exits the swallowing monster's space.

Effect: Engulf and Swallow Whole

If the monster dies, a swallowed creature can be freed by creatures adjacent to the corpse if they spend a combined total of 3 actions cutting the monster open with a weapon or unarmed attack that deals piercing or slashing damage.

Improved Grab —