Monolith, Earth (CR 17)

Gargantuan Elemental (Earth and Extraplanar)
Alignment: Usually neutral
Initiative: -2 (Dex); Senses: darkvision 60 ft., Listen +43, and Spot +43
Languages: Terran

AC: 25 (-4 size, -2 Dex, +21 natural), touch 4, flat-footed 25
Hit Dice: 36d8+255 (417 hp); DR: 15/-
Fort +27, Ref +10, Will +16
Speed: 30 ft.
Space: 20 ft./20 ft.
Base Attack +27; Grapple +55
Attack: Slam +40 melee
Full Attack: 2 slams +40 melee
Damage: Slam 6d8+15/19-20
Special Attacks/Actions: Earth mastery, push
Abilities: Str 43, Dex 6, Con 24, Int 12, Wis 15, Cha 17
Special Qualities: earth glide, elemental traits
Feats: Alertness; Awesome Blow; Cleave; Great Cleave; Improved Bull Rush; Improved Critical (slam); Improved Natural Attack; Improved Overrun; Improved Sunder; Iron Will; Power Attack; Toughness; Weapon Focus (slam)
Skills: Diplomacy +5, Intimidate +16, Jump +29, Listen +43, Sense Motive +15, and Spot +43
Advancement: 37-54 HD (Gargantuan)
Climate/Terrain: Elemental Plane of Earth
Organization: Solitary
Treasure/Possessions: None

Source: Complete Arcane

Earth Mastery (Ex): An earth monolith gains a +2 bonus on attack rolls and damage rolls if both it and its foe are touching the ground. If an opponent is airborne or waterborne, the monolith takes a -4 penalty on attack rolls and damage rolls.

Push (Ex): An earth monolith can start a bull rush without provoking attacks of opportunity. The combat modifiers given in Earth Mastery also apply to the monolith's opposed Strength checks.

Earth Glide (Ex): An earth monolith can glide through stone, dirt, or almost any other sort of earth except metal as easily as a fish swims through water. Its burrowing leaves behind no tunnel or hole, nor does it create any ripple or other signs of its presence. A move earth spell cast on an area containing a burrowing earth monolith flings the creature back 30 feet, stunning it for 1 round unless it succeeds on a DC 15 Fortitude save.

Earth monoliths are nearly unstoppable, using their great strength to crush and destroy their foes. Like other earth elementals, earth monoliths travel through solid ground or rock as easily as humanoids walk on the earth's surface.

They cannot swim, though, and must either walk around a body of water or travel through the ground beneath it.

Earth Subtype

This subtype usually is used for elementals and outsiders with a connection to the Elemental Plane of Earth. Earth creatures usually have burrow speeds, and most earth creatures can burrow through solid rock.

Extraplanar Subtype

A subtype applied to any creature when it is on a plane other than its native plane. A creature that travels the planes can gain or lose this subtype as it goes from plane to plane. This book assumes that encounters with creatures take place on the Material Plane, and every creature whose native plane is not the Material Plane has the extraplanar subtype (but would not have when on its home plane). An extraplanar creatures usually has a home plane mentioned in its description. These home planes are taken from the Great Wheel cosmology of the D&D game (see Chapter 5 of the Dungeon Master's Guide). If your campaign uses a different cosmology, you will need to assign different home planes to extraplanar creatures.

Creatures not labeled as extraplanar are natives of the Material Plane, and they gain the extraplanar subtype if they leave the Material Plane. No creature has the extraplanar subtype when it is on a transitive plane; the transitive planes in the D&D cosmology are the Astral Plane, the Ethereal Plane, and the Plane of Shadow.