I know I said Amargasaurus was next, but I realized that there was no Primal Magma Paraelemental, and how could I resist? Perfect for dropping into primeval volcanoes of any campaign world.
This took me about an hour to make. This is why I love elementals, they are the easiest epic monsters to make. For more information on these beasts and their lesser kin, look at the Magma Paraelemental entry in the Planar Handbook.
Spoiler
Primal Magma Paraelemental
Colossal Elemental (Fire, Earth, Extraplanar)
Hit Dice: 64d8+854 (1,142 hp)
Initiative: +7
Speed: 20 ft.
Armor Class: 49 (+48 natural, -8 size, -1 Dex), touch 1, flatfooted 49
Base Attack/Grapple: +48/+80
Attack: Slam +58 melee (4d10+16 damage 19-20/x2)
Full Attack: 2 Slams +58 melee (4d10+16 damage 19-20/x2)
Space/Reach: 30 ft./30 ft.
Special Attacks: Burn
Special Qualities: Elemental Traits, Damage Reduction 15/---, Spell Resistance 42
Saves: Fort +36, Ref +18, Will +26
Abilities: Str 43, Dex 8, Con 31, Int 4, Wis 13, Cha 13
Skills: Listen +33, Spot +34
Feats: Cleave, Great Cleave, Improved Bullrush, Improved Critical (Slam), Improved Sunder, Power Attack, Weapon Focus (Slam), Improved Toughness, Iron Will, Improved Initiative
Epic Feats: Overwhelming Critical, Epic Toughness (x5), Epic Prowess (x4), Epic Will, Superior Initiative
Environment: Elemental Planes of Fire and Earth
Organization: Solitary
Challenge Rating: 35
Treasure: None
Advancement: 65-288 HD (Colossal)
Level Adjustment: -----
A colossal mound of smoldering rock ascends from the lava flow below. Two tiny eyes can be seen in its primeval body.
Primal Magma Paraelementals are the most powerful of their kind.
Burn (Ex): Those grappled by a Magma Paraelemental or those hit with its slam attack must make a Reflex save (DC 52), or catch fire. This fire burns for 1d4 rounds. A burning creature can take a move-equivalent action to put out the flame. Creatures hitting a magma paraelemental with natural weapons or unarmed attacks take fire damage as though hit by the elemental’s attack, and also catch fire unless they succeed at a Reflex save. The DC is Constitution-based. Creatures hitting a magma paraelemental with natural weapons or unarmed attacks take fire damage as though hit by the elemental’s attack, and also catch on fire unless they succeed on a Reflex save.