Boneworm (CR 12)

Gargantuan Undead (Fire)
Alignment: Always chaotic evil
Initiative: -4 (Dex); Senses: Listen +5 and Spot +5
Languages: Boneworms have little interest in communicating with anyone, but they do understand the Common tongue.

AC: 17 (-4 size, -4 Dex, +15 natural), touch 2, flat-footed 17
Hit Dice: 18d12 (117 hp); DR: 15/magic
Fort +6, Ref +2, Will +11
Speed: 30 ft.
Space: 20 ft./15 ft.
Base Attack +9; Grapple +17
Attack: Slam +14 melee
Full Attack: Slam +14 melee
Damage: Slam 3d6+13
Special Attacks/Actions: Desiccation aura, disease, dreadful chanting
Abilities: Str 28, Dex 3, Con -, Int 5, Wis 10, Cha 17
Special Qualities: fire subtype, SR 20, undead traits
Feats: Power Attack
Skills: Climb +15, Listen +5, Spot +5, and Survival +3
Advancement: 19-36 HD (Gargantuan), 37-54 HD (Colossal)
Climate/Terrain: Warm desert and underground
Organization: Solitary
Treasure/Possessions: None

Source: Web

Desiccation Aura (Su): Living creatures within 30 feet of a boneworm are subject to the monster's desiccation aura. Each round, a victim of this aura must make a Fortitude save (DC 19) or suffer 1 point of Constitution drain as moisture seeps from his body through the skin and slips through the air toward the boneworm. The boneworm heals 5 points of damage each round its aura desiccates living creatures (despite the total amount of Constitution drain inflicted, since a portion of the moisture is lost to evaporation), gaining any excess as temporary hit points.

Disease (Ex): Any creature hit by a boneworm's slam attack must succeed at a Fortitude save (DC 19) or contract bonefire. The incubation period is instantaneous, and the disease deals 1d4 points of temporary Charisma damage and 1d4 points of temporary Constitution damage (see Disease, in the Dungeon Master's Guide). Victims of bonefire break into fevers as their bones pulsate with light and heat. They stink of cooked flesh, and their skeletons become visible from within their blistering bodies after two hours (unless the victim is treated effectively). Bonefire is highly contagious and is also transmitted by physical contact. Anyone who touches a person or creature diseased with bonefire (whether victims are alive or dead) must make a Fortitude save (DC 19) or catch the disease. A dead body remains infected with bonefire for a week after its death, whereupon the skeleton finally burns out in a spectacular flash of light. If at any time 18 or more bodies infected with bonefire are located within 30 feet of each other, the bodies rapidly meld together, as if drawn by a fell telekinesis, to a point at the center of the spread. Over the course of only 1 round, the bodies bind together and form a boneworm with a number of Hit Dice equal to the number of bodies that formed it.

Dreadful Chanting (Su): A boneworm's numerous mouths constantly chant half-remembered hymns and prayers. This chanting, consisting as it does of dozens of different hymns, sounds like a swarm of giant flies trying to mimic human voices with their buzzing. This effect unnerves and disturbs the living, especially those who can cast divine spells. A living creature within 90 feet of a chanting boneworm must make a Will saving throw (DC 19) against this mind- affecting, sonic fear effect or become shaken. Divine spellcasters suffer a -4 penalty on this saving throw. A shaken creature suffers a -2 penalty on all attack rolls, weapon damage rolls, and saving throws. Additionally, a divine spellcaster must make a successful Concentration check (DC 20 + spell level) to cast a spell in the area of the boneworm's chanting.

Fire Subtype: A boneworm is immune to fire damage but takes double damage from cold unless a saving throw for half damage is allowed. In that case, it takes half damage on a success and double damage on a failure.

A boneworm is a near mindless entity. The combined madness of the dozens of undead bodies that comprise its being leaves little room for organized thought or combat tactics. As a result, a boneworm simply slithers toward any living creatures it detects and attacks them by rearing up and slamming them with its body.

The dreaded boneworm is an amalgamation of dead desert-dwelling monks and priests. The insane tangle of bodies is fueled by a hatred of the deity and religion that failed to protect them all from starvation, thirst, and general insanity.

A boneworm is a massive creature that rarely measures less than 50 feet in length. Its wormlike shape consists of a mass of thousands of charred bones bound together by a thin membrane of tendons and scorched, leathery flesh. Hundreds of half-formed faces -- faces of the bodies the boneworm formed from -- press out of the leathery flesh at random points on the creature. These faces constantly contort into expressions of madness or rage, and they endlessly cry out twisted hymns and warped prayers to mock those deities they once revered.

The original boneworm came into existence when a large monastery located in the depths of a desert suddenly succumbed to a terrible disease known as bonefire. Some believe this disease came from one of the lower planes or even the Elemental Plane of Fire. In any case, the disease spread quickly, causing its victims to burn to death from the inside out as their skeletons became infused with terrible heat. It wasn't until after the victims died that the true purpose of the disease made itself known: The bodies of those who died of bonefire drew together and began to grow numerous new bones. The bones twisted together in a terrible braid of bone and dead flesh until it finally formed the monstrous abomination known as a boneworm.

Fire Subtype

A creature with the fire subtype has immunity to fire. It has vulnerability to cold, which means it takes half again as much (+50%) damage as normal from cold, regardless of whether a saving throw is allowed, or if the save is a success or failure.