Megapede (CR 20)
Alignment: Always neutral
Initiative: -2 (Dex); Senses: tremorsense, Listen +10, and Spot +7
AC: 18 (-8 size, -2 Dex, +18 natural), touch 0, flat-footed 18
Hit Dice: 32d8+256 (400 hp); DR: 15/magic adamantine
Fort +26, Ref +8, Will +11
Speed: 80 ft., burrow 20 ft.
Space: 100 ft./10 ft.
Base Attack +24; Grapple +56
Attack: 5 tentacle rakes +32 melee, or bite +32 melee
Full Attack: 5 tentacle rakes +32 melee, or bite +32 melee
Damage: Tentacle rake 2d8+16, bite 4d6+16 plus poison (DC 34)
Special Attacks/Actions: Poison
Abilities: Str 43, Dex 7, Con 27, Int -, Wis 12, Cha 4
Special Qualities: SR 31, vermin traits
Skills: Listen +10 and Spot +7
Advancement: 33-64 HD (Colossal)
Climate/Terrain: Warm desert
Monster Manual II
True terrors of the desert, megapedes constantly hunt the dunes and sandy plains for food. The desert offers little refuge to creatures fleeing these enormous predators.
A megapede looks like an enormous centipede with a long, segmented body and hundreds of pairs of legs. Its tough, bulbous body is covered with dense orange and brown bristles. The creature's tremendous mandibles twitch involuntarily when it senses prey. A megapede can grow to more than 100 feet in length.