Frost worm

Frost worms are monstrosities native to Wildemount's Biting North. These gargantuan creatures are ambush predators, lurking beneath the snow waiting for the telltale vibrations of prey passing overhead.

Appearance
Frost worms are enormous worms with purple flesh and white scales. They have no eyes, instead relying on their blindsight and tremorsense to detect prey.

Abilities

 * Multiattack: The worm makes two bite attacks, or uses its Trill and makes one bite attack.
 * Trill: The frost worm emits a haunting cry. Each creature within 60 feet of the worm that can hear it must succeed on a DC 20 wisdom save or be stunned for one minute. A stunned creature can repeat the save if it takes damage, and at the end of its turn. Once a creature successfully saves or the effect expires for it, that creature is immune to the Trill of all frost worms for the next 24 hours. Frost worms are immune to this effect.

The Mighty Nein encountered a frost worm as they traversed the isle of Foren in Eiselcross with their guide, Dagen Underthorn. After everyone but Jester was stunned by the worm's Trill, Jester successfully Polymorphed it. The party then fled from the creature while it was helplessly left as a turtle, spinning on its back on a frozen-over lake.