This large carpet of tangled threads tumbles forth like an avalanche of unsewn fabric.
Thread Swarm (CR 9)
N Fine construct (swarm) Init +2; Senses blind, blindsense 60 ft.; Perception +0
--- AC 23, touch 20, flat-footed 21 (+2 Dex, +3 natural, +8 size) hp 110 (20d10) Fort +6, Ref +8, Will +6 Defensive Abilities swarm traits; Immune cold, construct traits, sonic, weapon damage
--- Speed 30 ft., climb 30 ft. Melee swarm (4d6 plus distraction, stitches, and web) Special Attacks cling, distraction (DC 20), stitches, web (+22 ranged touch, DC 20, 20 hp)
--- Str 1, Dex 14, Con —, Int —, Wis 11, Cha 1 Base Atk +20; CMB —; CMD — Skills Climb +10; Racial Modifiers uses Dex on Climb checks
--- Environment any land or underground Organization solitary, pair, or carpet (3–6) Treasure none
--- Cling (Ex) If a creature leaves a thread swarm's square, the swarm takes 1d6 points of damage to reflect the loss of its numbers as several threads cling to the victim. A creature with threads clinging to it takes swarm damage at the end of its turn each round. As a full round action, the creature can remove the threads with a DC 20 Reflex save. At least 10 points of damage from an area effect that deals damage to which a thread swarm is not immune destroys all clinging threads. The save DC is Dexterity-based. Stitches (Ex) A thread swarm is filled with numerous small needles that place stitches in the flesh of its victims. Whenever a creature fails a saving throw against a thread swarm's distraction attack, that creature is cured of any bleed damage it is taking, but loses the use of its eyes and mouth as they are sewn shut. The use of the creature's eyes and mouth can be restored by a DC 15 Heal check, but only if the creature making the check wields a light slashing weapon or similar blade. Web (Ex) A thread swarm's web attack is effective against Large and smaller creatures. Whenever a creature fails a saving throw against a thread swarm's distraction attack, that creature is trapped as if hit by the thread swarm's web attack.
A thread swarm is made from thousands of animate strands of thread, each of which is a magical construct in its own right. These animate threads work as a collective to fulfill their intended purpose, usually the defense of a particular locale. A thread swarm mercilessly attacks intruders, trapping its victims in webs of sticky thread, piercing them with needles, and sewing stitches into their flesh.
The process for creating a thread swarm is not widely known, but is recorded in several obscure sources. The process is known to be both tedious and resource-intensive, as each swarm is a collection of thousands of individually-crafted constructs. The makers of thread swarms rely heavily upon magical spinning wheels, textile mills, and mechanical looms, as well as countless assistants who toil away in workshops devoted to the production of thread swarms.