Pathfinder Bestiary: Lodestone Slime

Over at The Piazza, Angel Tarragon recently posted a link to this Bearded Science Guy video, with the quip, "Imagine the horror on your players' faces when you beset a magnetic slime against the party!" I took that as a challenge to design a monster based on this experiment.

Lodestone Slime

This grayish black, amorphous blob's quivering flesh has a damp, metallic sheen. 

LODESTONE SLIME (CR 6)

XP 2,400
N Medium ooze (earth)
Init -5; Senses blindsight 60 ft., scent metals; Perception -5
Aura magnetism (20 ft.)

Defense
AC 14, touch 4, flat-footed 14 (-5 Dex, +10 natural, -1 size)
hp 76 (8d8+40)
Fort +7, Ref -3, Will -3
Defensive Abilities ooze traits; DR 5/magic; Immune blindness, fire, mind-affecting effects
Weaknesses ferrous

Offense
Speed 20 ft., burrow 10 ft.; metal walk
Melee slam +9 (1d8+6 plus 1d6 acid)
Space 10 ft.; Reach 5 ft.
Special Attacks acid
Statistics

Str 18, Dex 1, Con 20, Int —, Wis 1, Cha 1
Base Atk +6; CMB +11 (+13 magnetism); CMD 16 (26 vs. bull rush with metal walk, can't be tripped)
SQ no breath, ooze traits
Ecology

Environment any underground

Organization solitary

Treasure none

Special Abilities

Acid (Ex) A lodestone slime secretes a digestive acid that dissolves organic material and metal quickly, but does not affect stone. Each time a creature suffers damage from a lodestone slime's acid, its clothing and armor take the same amount of damage from the acid. A DC 19 Reflex save prevents damage to clothing and armor. A metal or wooden weapon that strikes a lodestone slime takes 1d6 acid damage unless the weapon's wielder succeeds on a DC 19 Reflex save. If a lodestone slime remains in contact with a wooden or metal object for 1 full round, it inflicts 10 points of acid damage (no save) to the object. The save DCs are Constitution-based.

Ferrous (Ex) A lodestone slime's body is largely composed of iron. It is affected by rust attacks, such as those of a rust monster or a rusting grasp spell.

Magnetic Grab (Ex) A lodestone slime's body exerts a powerful magnetic force, holding fast any metal creatures or items that strike it. A metal weapon that strikes a lodestone slime is stuck fast unless the wielder succeeds on a DC 18 Reflex save. A successful DC 18 Strength check is needed pry off a stuck weapon. The save DC is Strength-based.

Magnetism (Ex) Any metal object or creature that is brought within 20 ft. of a lodestone slime is pulled towards the ooze by an invisible force similar to a constant telekinesis effect. Magnetism affects any Large or smaller metal item or creature when it first enters the aura, and again on the ooze's turn each round. Unattended and unsecured objects are automatically pulled 5 feet closer to the ooze if Large or Medium, 10 feet if Small or Tiny, or 20 feet if Diminutive or smaller.

     For metal creatures, or metal objects held or worn by a creature, resolve the magnetism attack as a combat maneuver. The lodestone slime's Combat Maneuver Bonus for this effect is +13, which includes a +2 racial modifier. On a successful combat maneuver, the metal creature or the metal object's bearer is pulled toward the ooze as above. If the combat maneuver is successful against a held item (such as a metal weapon), treat the result as a successful disarm unless the wielder makes a successful DC 18 Strength check. On a successful check, the creature retains hold of the item, but is pulled toward the ooze (at a speed determined by the bearer's size rather than the object's size, unless the object is larger). The Strength check DC is Strength-based.

     Against unattended but secured objects (such as a chain fastened to a wall), make a combat maneuver check against the item's break DC. On a success, the object breaks or is otherwise pulled loose, and moves toward the lodestone slime as above.

Metal Walk (Ex) Due to its magnetic nature, a lodestone slime can cling to and move at its base speed across metal surfaces, even those that are perfectly smooth or inverted. When using metal walk, the ooze gains a +10 circumstance bonus to its Combat Maneuver Defense against bull rush, awesome blows, and other attacks and effects that attempt to physically move it from its location.

Scent Metals (Ex) This ability functions much the same as the scent ability, except that the range is 90 feet and the lodestone slime can only use it to sense metal objects (including creatures wearing or carrying metal items).

A lodestone slime's viscous body is heavily infused with ferrous minerals that emit a powerful magnetic field. Its bizarre metabolism requires it to consume copious amounts of both metal (in order to maintain its magnetic powers) and flesh (in order to heal and maintain its mobility). A lodestone slime completely deprived of all nourishment will eventually decay into a brittle mass of inert slag.

Rust monsters can scent the metallic body of a lodestone slime at twice their normal range, and will be irresistibly drawn to attack and devour these oozes. Gorging on the slime's rusted remains may have unusual effects on the rust monsters or their offspring, manifesting as the advanced or giant template, or some more bizarre mutation.

Design Notes

I borrowed pieces from several existing monsters in order to devise the lodestone slime's various abilities:

• Scent metal is taken from the rust monster. 
• Like the iron golem, the lodestone slime is a ferrous creature, so is affected by rust attacks.
• Metal walk is modeled after the black pudding's suction ability.
• The acid attack is based on the gray ooze (which is Large, has 6 HD, and affects flesh and metal).
• Magnetic grab is modeled after the mimic's adhesive ability.
• The idea for using combat maneuvers for the magnetism aura came from the telekinesis spell, which seemed to be the closest analogy in the Core Rulebook spell list.

And finally, this creature has not yet been playtested at all, so I'd appreciate any feedback that you may have about the build.