Boneyard (CR 14)

Huge Undead
Alignment: Always chaotic evil
Initiative: +6 (+2 Dex, +4 Improved Initiative); Senses: darkvision 60 ft., Listen +25, and Spot +25

AC: 30 (-2 size, +2 Dex, +20 natural), touch 10, flat-footed 28
Hit Dice: 17d12+17 (127 hp); DR: 10/-
Fort +7, Ref +9, Will +15
Speed: 20 ft., fly 60 ft. (good)
Space: 15 ft./10 ft.
Base Attack +8; Grapple +26
Attack: Bite +16 melee
Full Attack: Bite +16 melee
Damage: Bite 2d8+15/19-20 plus bone subsumption
Special Attacks/Actions: Bone subsumption, improved grab, summon skeletons, utter subsumption
Abilities: Str 31, Dex 14, Con -, Int 18, Wis 20, Cha 18
Special Qualities: fast healing 10, immunity to cold, inescapable craving, SR 24, undead traits
Feats: Combat Reflexes; Dodge; Great Fortitude; Improved Critical (bite); Improved Initiative; Improved Toughness; Lightning Reflexes
Skills: Balance +22, Climb +30, Hide +22, Jump +30, Listen +25, Move Silently +22, Search +24, and Spot +25
Advancement: 18-25 HD (Huge); 26-51 HD (Gargantuan)
Climate/Terrain: Any
Organization: Solitary
Treasure: Standard

Source: Libris Mortis

The pile of bones before you stirs. The bones rise and reform, and as each bone finds its proper place, the shape of a huge serpentine creature emerges, one whose form is composed of interlocking bones, its head the skull of some unnamed and long-dead beast.

A boneyard is an undead creature made entirely from the bones of other dead creatures. However, unlike a skeleton or similar monster, a boneyard's form is fluid in the sense that it can appear merely as a pile of bones, or as a serpent composed of bones, or some other form of its choice. Boneyards have been called by many names, depending upon where they are encountered, including bone weirds, dancing bones, and bonetakers.

A boneyard weighs between 4,000 and 8,000 pounds, depending on the number of bones it has subsumed.

Boneyards speak Common, Terran, and Abyssal.