Icy Prisoner (CR 5)

Medium Undead (Cold)
Alignment: Always chaotic evil
Initiative: +6 (+2 Dex, +4 Improved Initiative); Senses: darkvision 60 ft., Listen +6, and Spot +6

AC: 19 (+2 Dex, +7 natural), touch 12, flat-footed 17
Hit Dice: 7d12 (45 hp)
Fort +2, Ref +6, Will +6
Speed: 30 ft., burrow 30 ft., swim 30 ft.
Space: 5 ft./5 ft.
Base Attack +3; Grapple +11
Attack: Claw +7 melee
Full Attack: 2 claws +7 melee and bite +2 melee
Damage: Claws 1d6+4 plus 1d6 cold plus frostbite, and bite 1d4+2 plus 1d6 cold plus frostbite
Special Attacks/Actions: Cold, create spawn, frostbite, improved grab
Abilities: Str 18, Dex 14, Con -, Int 10, Wis 13, Cha 15
Special Qualities: immunity to cold, undead traits, vulnerability to fire
Feats: Improved Initiative; Lightning Reflexes; Power Attack
Skills: Balance +12, Hide +12, Listen +6, Move Silently +12, and Spot +6
Advancement: 8-10 HD (Medium)
Climate/Terrain: Cold aquatic
Organization: Solitary or pack (2-9)
Treasure: None

Source: Dragon #324

Erupting in an explosion of ice and snow, a slick, frost bitten body bursts from the frozen waters below. It glares at you with cold eyes and hefts its ice-encrusted corpse in your direction.

Icy prisoners are undead creatures created from the bodies of those drowned in icy lakes, ponds, or streams. These creatures spend most of their existences morbidly bobbing below the ice of their watery tombs, waiting to ambush and drown passersby who come too near.

Icy prisoners appear as grotesque, humanoid forms entombed in ice-covered bodies of water. The dead, frostbitten skin of these forms lies pallid beneath the useless tatters of their remaining winter clothing. From a face sickly discolored by extreme cold, an icy prisoner's eyes glow with a pale, watery blue illumination, and their lingering hair hangs down frozen to their sallow faces.

Cold Subtype

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