Armor Class 14
Hit Points 58 (9d10 + 9)
Speed 40 ft., fly 40 ft.
Skills Perception +3, Stealth +6
Damage Immunities cold
Senses Darkvision 60 ft., passive Perception 13
Languages understands Primordial but can't speak
Challenge 3
Misty Slithering. The serpent can move through a space as narrow as 1 inch without expending extra movement to do so.
Multiattack. The serpent makes one Bite attack and uses Constrict.
Bite. m +6, reach 5 ft. Hit: 8 (1d8 + 4) Piercing damage plus 3 (1d6) Cold damage.
Constrict. str DC 14, one Medium or smaller creature the snake can see within 10 feet. 3 (1d6) Bludgeoning damage plus 7 (2d6) Cold damage. The target has the Grappled condition (escape DC 14), and it has the Restrained condition until the grapple ends.
FRAiF, p. 269