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Kaiju, Yarthoon

This immense pale blue worm raises one end of its body like a serpent, its many-toothed maw opening amid a ring of glowing eyes.

Yarthoon CR 25

Source Bestiary 6 pg. 174
XP 1,638,400
CN Colossal magical beast (air, kaiju)
Init +13; Senses low-light vision, mistsight, see in darkness, tremorsense 300 ft.; Perception +28


AC 44, touch 12, flat-footed 34 (+9 Dex, +1 dodge, +32 natural, –8 size)
hp 565 (29d10+406); fast healing 30
Fort +30, Ref +25, Will +19
Defensive Abilities ferocity, recovery; DR 20/epic; Immune ability damage, ability drain, cold, death effects, disease, energy drain, fear; Resist acid 30, electricity 30, fire 30, negative energy 30, sonic 30


Speed 60 ft., burrow 100 ft., fly 100 ft. (average), swim 100 ft.
Melee 2 bites +39 (4d6+27/19–20 plus 4d6 cold and grab), slam +39 (4d8+27/19–20 plus 4d6 cold and staggering strike)
Space 30 ft., Reach 30 ft.
Special Attacks clinging frost, eye beams, fast swallow, freezing mist, hurl foe, penetrating cold, swallow whole (6d6 bludgeoning and 6d6 cold damage, AC 26, 56 hp), swift bite


Str 46, Dex 29, Con 38, Int 3, Wis 26, Cha 21
Base Atk +29; CMB +55 (+59 overrun); CMD 75 (77 vs. overrun, can’t be tripped)
Feats Critical Focus, Dodge, Flyby Attack, Greater Overrun, Improved Critical (bite, slam), Improved Initiative, Improved Iron Will, Improved Overrun, Improved Vital Strike, Iron Will, Power Attack, Staggering Critical, Vital Strike, Wingover
Skills Fly +32, Perception +28, Swim +26; Racial Modifiers +16 Perception
Languages Auran (can’t speak)
SQ massive, no breath, powerful blows (bite, slam), starflight


Environment any cold (the world’s moon or outer space)
Organization solitary (unique)
Treasure incidental

Special Abilities

Clinging Frost (Su) Whenever a creature takes cold damage from Yarthoon (including from her freezing mist), the creature becomes encrusted with a layer of clinging frost for 1 round. The duration of this clinging frost stacks with multiple instances of cold damage from Yarthoon. As long as a creature has at least 1 round of clinging frost remaining, it takes a –2 penalty on all Reflex saving throws and Dexterity-based skill checks. As long as a creature has at least 2 rounds of clinging frost remaining, it is staggered. Freedom of movement negates the effects of clinging frost, and if a creature activates a firebased supernatural ability on its turn, it reduces the number of rounds remaining by 1d4. Creatures with the fire subtype, the heat ability, or any similar ability to shed significant warmth are immune to clinging frost.

Eye Beams (Su) Once every 4 rounds as a standard action, Yarthoon can emit several beams of freezing energy from her eyes. When Yarthoon uses this attack, she can choose to fire all of the beams in one direction to create a single line 1,200 feet long, or she can instead fire eight separate beams as ranged touch attacks with a range of 1,200 feet. If she chooses to fire them in a line, all creatures within the area of effect take 20d6 points of cold damage (Reflex DC 38 half). If she fires the beams as ranged touch attacks, she has a +30 attack bonus but can target a single creature with no more than two eye beams at a time (though she can fire the beams in any direction to attack multiple targets in range). A single eye beam deals 8d6 points of cold damage on a hit (no save). The save DC for the line-based attack is Constitution-based.

Freezing Mist (Su) Once per day as a swift action, Yarthoon can exhale a cloud of freezing mist, filling a 200-foot-radius sphere surrounding her. This mist obscures vision as per obscuring mist and persists for 10 rounds, and is not dispersed by moderate wind. A strong wind (21+ mph) disperses the mist in 2d4 rounds, while fireball, flame strike, or similar spells burn away the mist in the spell’s area. Any creature within the area of the mist when Yarthoon creates it takes 8d6 points of cold damage (Reflex DC 38 half). A creature that begins its turn within the mist takes 4d6 points of cold damage (no save) at the start of its turn. The save DC is Constitution-based.

Penetrating Cold (Su) When Yarthoon deals cold damage, the damage ignores the first 30 points of cold resistance the target has.

Staggering Strike (Ex) If Yarthoon hits a Gargantuan or smaller foe that’s standing on the ground with her slam attack, the target struck must succeed at a DC 42 Reflex save or be knocked prone and become staggered for 1d6 rounds. If she hits a Gargantuan or smaller flying foe, the creature is staggered for 1d6 rounds and must succeed at a DC 42 Fly check or lose 30 feet of altitude (a winged flying creature loses 60 feet of altitude instead; this replaces the normal rule for being attacked while flying for winged creatures). A Colossal creature struck by Yarthoon’s slam must succeed at a DC 42 Reflex save to resist being staggered for 1 round, but is not knocked prone or forced to lose altitude. The save DC is Strength-based.

Starflight (Su) Yarthoon can survive in the void of outer space. She flies through space at incredible speeds, but generally only does so to travel between the moon and the world below when her attention is caught or her curiosity piqued. It takes Yarthoon only 2d4 hours to travel from the moon to the world below. If she were to travel to a more distant point in the same solar system, she requires only 3d6 days to make the journey, while trips beyond this range generally take her 3d6 weeks.

Swift Bite (Ex) Yarthoon strikes with astonishing speed when she attacks with her bite. Whenever Yarthoon makes a bite attack on her turn, she can attack two times, either as a standard action to bite twice, or as part of a full attack to bite two times in addition to making one slam attack. She can make any number of attacks of opportunity with her bite attack, but does not get to bite more than once when she does so.


Yarthoon is among the least powerful of the kaiju, yet even she is of staggering size and capable of unleashing devastation on an apocalyptic scale. Known as the Moon Grub to kaiju scholars, Yarthoon does indeed dwell upon the moon itself, where she spends much of her time in a frozen reach of ice and snow, created, in part, by her presence and the effects of her freezing breath over the course of centuries. (Note that although Yarthoon’s exhalations fill the region with freezing mist, the Moon Grub herself has no need to breathe and can exist comfortably in the vacuum of space.)

Were Yarthoon content to remain upon the moon, there would be little known about the frozen kaiju; unfortunately, the larger world her home orbits is a constant fascination for her. Indeed, certain events have been known to specifically attract Yarthoon’s attention, whether they’re intentional calls such as powerful rituals led by apocalyptic cultists, or accidental lures that occur when powerful effects of magical cold occur. The exact nature of these attractions varies, and even the most learned scholars argue over what exactly it is that draws Yarthoon to visit the world. None, however, dispute the devastation Yarthoon unleashes, if unintentionally, when she visits the world. Unlike many kaiju, Yarthoon seems not to purposefully seek out civilizations to destroy, but her immense size and her freezing breath wreak havoc nonetheless. Fortunately, Yarthoon’s visits to the world typically last for only a few days before she slithers off into the sky like an eel swimming through water to return to her den on the moon.

Yarthoon has a complex relationship with Mogaru, the Final King (Pathfinder RPG Bestiary 4 170). Often, Mogaru’s devastation on a region is enough to lure Yarthoon down from the moon, in which case she often clashes with the more powerful kaiju. Likewise, Mogaru’s ability to sense kaiju often results in him coming to investigate a region that Yarthoon has decided to visit. Yet the two kaiju never seem willing to finish a fight against the other, and rather than deliver a death blow when the chance rises, each seems content to let the other flee. The one thing that seems to unite the two kaiju is their shared hatred of Lord Varklops, and the two kaiju have teamed up several times to drive off the three-headed fiend more than once.

Although Yarthoon is the least powerful of the known kaiju, the Moon Grub has been remarkably resilient. Time and time again, Yarthoon has returned after suffering what seemed to be a complete defeat, at either the hands of powerful heroes or the claws and fangs of fellow kaiju. Scholars of these immense monsters have theorized that Yarthoon may not be a unique creature, and that in its hidden lair on the moon, multiple Moon Grubs writhe and dream. Others posit that Yarthoon is but the larval stage of a kaiju, and that while only one may live at any time, numerous other eggs lie in a hidden crèche on the moon, waiting to hatch and release replacement Moon Grubs as needed.

Yarthoon is 250 feet long from head to tail and weighs 14,000 tons.

Creatures in "Kaiju" Category



Source Bestiary 4 pg. 165
In the furthest reaches of the globe, where civilization itself is a legend and mapmakers can only make guesses about lands and denizens, immense creatures that are worshiped as gods walk the world. Capable of devastating entire cities in a single day of ruin and unleashing powerful supernatural attacks, these fabled, so-called “gods” are anything but. These massive monsters are known as kaiju, and the tales told of their genesis are as varied as the strange forms and capabilities of the monsters themselves.

A kaiju is a monster of tremendous size—far larger than almost any other creature. Each kaiju is unique, but they all share a few traits in common (see the kaiju subtype on page 307). Kaiju can be of different types, but most are magical beasts. Although kaiju are semiintelligent and can generally understand a single language, they cannot speak. Some legends tell of certain gifted or unique people being able to call kaiju from vast distances to aid them in times of distress. This type of bond with a kaiju isn’t well understood, but rarely comes to those who already possess great power. Rather, it is the helpless, the compassionate, and the meek who can bring forth kaiju.

Kaiju generally dwell in distant, remote wildernesses, often in unusually close proximity to one another. There they battle, but never quite seem to finish their constant conflicts before one of the beasts staggers away to recover from the clash, defeated only for the moment. Visitors to one of the remote lands where kaiju frequently clash can often explore without too much fear, as long as they take care not to be too visible or destructive as they explore. Unless a kaiju is being attacked or is particularly aggressive (such as when it’s defending a territory), it’s likely to ignore Medium or smaller creatures that wander in its vicinity, just as a human might ignore an ant crawling nearby.

A kaiju’s supernatural metabolism allows it to draw energy and nutrition from sources other than food— each kaiju “feeds” in a different way on a different form of energy, but when denied its energy source it does not starve. Instead, the immense monster simply falls into torpor, hibernating until a new source of energy awakens it once again. In some cases, a kaiju can lie dormant for ages—so long that civilizations have time to unknowingly encroach upon lands the monster claimed long ago as its territory. As long as the new civilizations take care to not accidentally waken the monster, they can coexist with the slumbering kaiju in relative peace for many, many years. Yet eventually, some event will inevitably waken the slumbering giant and call it forth into a rampage.

Certain events can drive a kaiju into a destructive frenzy. Powerful storms or natural disasters, rare and dangerous rituals designed to call out to them, the use of incredibly powerful magical weapons, wars, and the approach of other kaiju can all send one of these creatures on a rampage of wrath. When a kaiju begins such a rampage, it leaves its remote wilderness home and travels far afield, often for hundreds or even thousands of miles through unexplored wilds or across entire oceans until it reaches the source of the irritation.

Upon arriving in such a location, the kaiju seeks out the source of whatever enraged it, or if no obvious source is apparent, it simply tramples a path of destruction through whatever city or fortress or locale happens to be in its way. Once a kaiju’s rampage begins, it can last for weeks, with the monster periodically retreating between attacks into wildernesses or oceans near the source of the disturbance to rest or recuperate.

Societies that are frequently plagued by kaiju attacks often build special magical siege engines designed to drive off the monster, or even seek to recruit the aid of other kaiju to battle the intruder. Unfortunately, the collateral damage caused by multiple kaiju is significant, and fighting fire with fire in this way may leave behind nothing but rubble.

All kaiju are Colossal, and have a space and reach of no less than 50 feet each. A bipedal kaiju typically stands between 100 and 200 feet in height; quadrupedal kaiju are half as tall. A kaiju’s size makes a battle against one challenging to run. At the scale needed to track tactical movement for Medium creatures, a kaiju takes up a massive amount of space. When designing an encounter with a kaiju, plan ahead and prepare a larger area so that you can track the kaiju’s movement effectively.

Known Kaiju

The kaiju presented on the following pages are but three of the legendary creatures said to dwell in remote places in the world. Here is a list of others, including the places they’re rumored to dwell.

Agmazar, the Star Titan of the vast jungle
Cimurlian, the Great Bear of the frozen north
Ebeshra, the Winged Razor of the furthest clouds
Igroon, the Dragon Eater of the lost island
Mantraska, the World Talons of the rain forest
Shbloon, the Vortex Maw of the ocean deep
Lord Varklops, the Thrice-Headed Fiend of the dormant volcano
Queen Vorgozen, the Shapeless Feeder of the vast swamp
Yarthoon, the Moon Grub of the darkest nights
Yorak, the Horned Thunder of the great mountains
Zimivra, the Endless Coils of the trackless desert