Entombed (CR 10)

Large Undead (Cold)
Alignment: Usually lawful evil
Initiative: +0; Senses: darkvision 60 ft., tremorsense 60 ft., Listen +21, and Spot +21

AC: 24 (-1 size, +15 natural), touch 9, flat-footed 24
Hit Dice: 16d12 (104 hp)
Fort +7, Ref +5, Will +12
Speed: 30 ft., burrow 40 ft. (ice only)
Space: 10 ft./10 ft.
Base Attack +8; Grapple +20
Attack: Slam +15 melee
Full Attack: 2 slams +15 melee
Damage: Slam 2d6+8 plus 2d6 cold
Special Attacks/Actions: Create spawn, freeze, icy touch, immure, improved grab
Abilities: Str 27, Dex 10, Con -, Int 11, Wis 14, Cha 12
Special Qualities: ice glide, immunity to cold, undead traits, vulnerability to fire
Feats: Awesome Blow; Cleave; Great Fortitude; Improved Bull Rush; Improved Sunder; Power Attack
Skills: Hide +15, Listen +21, Move Silently +19, and Spot +21
Advancement: 17-32 HD (Large)
Climate/Terrain: Cold mountains
Organization: Solitary or pair
Treasure: Standard

Source: Frostburn

A thick shell of clear green-tinged ice completely encases a desiccated human corpse, its yellowed teeth bared in a rictus of death. The huge mantle of icy armor makes this fearsome apparition the size of an ogre.

The entombed are undead preserved by being encased in shells of ice - but still able to move and kill.

Entombed are human or humanoid undead entirely frozen inside an icy sheath that gives them the stature of an ogre. The face of one of these creatures is usually frozen in a rictus of fear or sorrow - its flesh, hair, and eyes are always very well preserved, though the skin sometimes takes on a frozen whitish tone.

Entombed do nor speak, but are able to hear others through their icy coating. They understand Common.

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.