This immense white worm has a single circular eye in the center of its head. Wisps of icy fog waft up from between its mandibles.
Frost Worm CR 12
Init +7; Senses darkvision 60 ft., low-light vision; Perception +17
AC 27, touch 11, flat-footed 24 (+3 Dex, +16 natural, –2 size)
hp 168 (16d10+80)
Fort +15, Ref +13, Will +10
Weaknesses vulnerable to fire
Speed 30 ft., burrow 10 ft.
Melee bite +25 (4d10+15 plus 4d6 cold)
Space 15 ft.; Reach 10 ft.
Str 31, Dex 16, Con 21, Int 2, Wis 16, Cha 11
Base Atk +16; CMB +28; CMD 41 (can't be tripped)
Environment cold plains or mountains
Cold (Su) A frost worm's body generates intense cold, allowing it to deal an additional 4d6 cold damage with its bite attack. Any creature that attacks a frost worm with an unarmed strike or a natural weapon takes 1d6 points of cold damage per successful hit. A creature that grapples or is grappled by a frost worm takes 4d6 points of cold damage per round the grapple is maintained.
Death Throes (Su) When killed, a frost worm explodes in a 100-foot-radius burst that deals 12d6 cold damage and 8d6 piercing damage (DC 23 Reflex half). The save DC is Constitution-based.
Trill (Su) As a full-round action, a frost worm can emit a strange trilling sound that affects all creatures within a 100-foot radius. Creatures must succeed on a DC 18 Will save or be fascinated for as long as the worm continues to trill (the frost worm can maintain this trill by concentrating). Once a creature has resisted or broken the effect, it cannot be affected again by that same frost worm's trill for 24 hours. This is a sonic mind-affecting effect. The save DC is Charisma-based.
With armor-crushing jaws, flesh that radiates cold, and a terrible keening cry capable of holding creatures fascinated, frost worms are apex predators of the frozen tundra and glaciers. In the frost worms' far-reaching hunting grounds, they fear only the remorhaz, for the heat generated by an enraged remorhaz causes intense pain to a frost worm.
This extreme aversion to heat, as well as its freezing touch and devastating breath weapon, stems from an unusual facet of frost worm physiology—veins that run with magically cold blood. This creature's ichor is clear, but infused with such sub-freezing temperatures that the monster's flesh can freeze water in the skin of creatures that touch it. When a frost worm dies, this magical energy dissipates, and both blood and muscle immediately freeze solid and then explode into a catastrophic barrage of icy shrapnel. As a result, even those predators that might legitimately prey upon the burrowing monstrosities tend to leave frost worms well enough alone.
An adult frost worm measures 35 feet long and weighs 8,000 pounds.