Steel Ooze
The heat from the large pool of molten metal is palpable from a distance—and then it starts to move.

Steel Ooze (CR 6; XP 2,400)
N Large ooze (fire)
Init +1; Senses blindsight 60 ft.; Perception -5
Aura heat (10 ft., 1d4 fire)
AC 10, touch 10, flat-footed 9
(+1 Dex, -1 size)
hp 75 (10d8+30)
Fort +6, Ref +4, Will -2
Defensive Abilities absorb metal, weapon bane; Immune fire, mind-affecting, ooze traits
Vulnerable cold
Speed 20 ft.
Melee 2 slams +10 (1d6+4 plus 1d6 fire)
Space 10 ft.; Reach 15 ft.
Special Attacks firefall
Spell-Like Abilities (CL 10th; concentration +5)
At-will—quickened heat metal
Str 19, Dex 13, Con 17, Int —, Wis 1, Cha 1
Base Atk +7; CMB +12; CMD 23 (can’t be tripped)
Environment mountain, underground
Organization solitary
Treasure none
Special Abilities
Absorb Metal (Ex) If the steel ooze strikes an opponent wearing metal amor, it attempts to absorb part of the armor. If the target fails a Reflex save DC 18, the armor loses one point of armor bonus. Magical armors may add their enhancement bonus to the save. For every point of armor absorbed the steel ooze heals 5 points of damage. The save DC for this ability is Constitution-based.
Firefall (Ex) As a standard action, the steel ooze can cause itself 1d6 points of damage, to shower all foes within 20 ft. of it with a rain of molten steel. All creatures within this area are allowed a Reflex save DC 18 to negate this damage. Those that fail suffer 4d6 points of fire damage this round, 3d6 the next, 2d6 on the third round, and 1d6 on the final round. The save DC is Constitution-based.
Weapon Bane (Ex) Metal weapons that strike a steel ooze takes 1d6 points of fire damage that ignores the hardness of the metal. Wooden weapons immediately catch fire upon contact with the ooze and take 1d6 points of fire damage until extinguished. Magical weapons receive a Fortitude save DC 18 to resist all the damage. They may add their enhancement bonus to the save. The save DC is Constitution based.

Living pools of bubbling metallic protoplasm, steel oozes are usually found deep underground, feeding on veins of ore at warm depths. Mining expeditions that encounter them are typically ignored unless they carry metal—the more refined the better. Steel oozes are dangerous and can cause tunnel timbers to burn and collapse, and deal a great deal of damage to mineworks just by their presence. Some variants live above ground, in desert or tropical mountain ranges made of ore-bearing stone.

On Porphyra
Dwarves on Porphyra call steel oozes zarg na Feraku- the blood of Ferrakus- and treat them with a kind of holy dread, though they attempt to dispatch them as soon as they are found with a dwarven recipe for liquid ice and sling stones. A steel ooze killed with cold becomes a metal slag that has many uses, kept secret by dwarves. The deep tunnels below Argentum in Creeper’s Rift, and most of the Underdeep are where steel oozes lurk.