Sthira

When a creature dies while it has persistent cold damage from the sthira's frostbite, the creature rises as a sthira in 24 hours. If the creature is grabbed by the sthira when it dies, the dying creature becomes permanently fused with the sthira instead. In this case, the sthira immediately recovers a number of Hit Points equal to the half the dead creature's maximum Hit Points.

Trigger A creature within the monster's reach uses a manipulate action or a move action, makes a ranged attack, or leaves a square during a move action it's using. Effect The monster attempts a melee Strike against the triggering creature. If the attack is a critical hit and the trigger was a manipulate action, the monster disrupts that action. This Strike doesn't count toward the monster's multiple attack penalty, and its multiple attack penalty doesn't apply to this Strike.

A creature that damages the sthira with an unarmed attack, tries to Grapple it, or otherwise touches it takes 6d6 cold damage (DC 42 fortitude save).

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.

20 feet. A creature that starts its turn in the aura takes 6d6 cold damage (DC 42 fortitude save). If the creature is grabbed or restrained by the sthira, it takes one degree of success worse than it rolled.

A creature that takes cold damage from a sthira's Strikes or aura must attempt a DC 42 fortitude save. A creature that already has persistent cold damage from frostbite ignores this effect. Critical Success The creature is unaffected, and is temporarily immune to this ability for 1 hour. Success The creature is unaffected. Failure The creature takes 3d6 persistent cold damage. Critical Failure As failure, but the creature is also Drained 1.

Trigger The monster's last action was a successful Strike that lists Improved Grab in its damage entry, or the monster has a creature Grabbed or Restrained Effect If used after a Strike, the monster attempts to Grapple the creature using the body part it attacked with as a free action. This attempt neither applies nor counts toward the creature's multiple attack penalty. The monster can instead use Improved Grab as an action and choose one creature it's grabbing or restraining with an appendage that has Improved Grab to automatically extend that condition to the end of the monster's next turn.