Ferruginous Blob

Ferruginous Blob
No. Enc.: 1d2 (1d6)
Alignment: Chaotic
Movement: 20' (6')
Armor Class: 7
Hit Dice: 2+
Attacks: 1
Damage: 1d8 or by weapon (Plus rust effect)
Save: F2
Morale: 10

Weird amorphous horrors that lurk far beneath the mapped or traveled sections of the deep dark, Ferruginous Blobs are the degenerate spawn of things that withdrew from conventional subterranean society long, long ago in order to pursue their bizarrre vocation; they create peculiar, non-ferrous enchanted weapons suited pretty much only to their own use.

Acutely aware of vibration and magnetism, the Ferruginous Blobs also possess highly developed olfactory senses and have countless tiny overlapping taste-buds scattered randomly across their outer membranes. They can detect iron from more than a mile away. Even underground. And they have an unholy, unquenchable appetite for the stuff.

Any normal, non-enchanted iron or steel that comes into contact with a Ferruginous Blob will only do so once, which will allow weapons to inflict their damage, but then they will crumble into rust that the creature will attempt to absorb. Enchanted iron/steel gains a Save, and must lose its magical bonuses 1 at a time, as per a Rust Monster's attack (LL, p. 93-94).

A typical Ferruginous Blob will be wielding a +1 weapon fashioned from some strange alloy that might be an esoteric form of bronze, or something else entirely. So far the two samples recovered have defied all attempts at alchemical analysis.

Ferruginous Blobs usually gain an additional +1 bonus or extra special ability for their weapon every other HD.

According to some sources, these things gain extra HD from destroying enchanted steel weapons, but this is probably just another old Midwives' tale.