Earthcancer Centipede (CR 13)

Gargantuan Undead
Alignment: Always neutral evil
Initiative: +8 (+4 Dex, +4 Improved Initiative); Senses: darkvision 60 ft., tremorsense 120 ft., Listen +27, and Spot +0

AC: 30 (-4 Size, +4 Dex, +15 natural, +5 haste), touch 15, flat-footed 26
Hit Dice: 24d12 (156 hp); DR: 15/silver
Fort +10, Ref +14, Will +16
Speed: 60 ft., burrow 60 ft.
Space: 20 ft./15 ft.
Base Attack +12; Grapple +33
Attack: 2 bites +17 melee
Full Attack: 2 bites +17 melee
Damage: 2 bites 4d6+13/19-20 plus poison
Special Attacks/Actions: earthcancer aura 60 ft.
Abilities: Str 18, Dex 18, Con -, Int 2, Wis 10, Cha 14
Special Qualities: Alacrity, obey the wormtouched, undead traits, fast healing 10;
Feats: Combat Reflexes; Dodge; Great Fortitude; Improved Critical (bite); Improved Initiative; Iron Will; Lightning Reflexes; Mobility; Spring Attack
Skills: Listen +27 and Spot +0
Advancement: 25-32 HD (Gargantuan), 33-72 HD (Colossal)
Climate/Terrain: Wormcrawl Fissure
Organization: Solitary, pair, or brood (3-12)
Treasure: None

Source: Dungeon #134

A thirty-five-foot-long pale green and white centipede scuttles sinuously over the barren earth. Its dark green eyes peer above a nest of several long antennae writhing on its face. Tiny green worms drip from its mouth and cracks in its chitinous armor, and at places where it stands or touches the rock walls, the earth turns gray and boils into nasty, tumor-like growths of pale fungus.

Earthcancer centipedes are the result of Kyuss' attempt to generate undead useful in sieges. An earthcancer centipede is thirty-five feet long and weighs 18 tons.