From the  Physiologus Veritas  of the sage
Baerdalumi, with notes appended by the
author:
 
 

Dragon magazine	-	Monster Manual III	-	Dragon #88
-	-	Notes	-	-

The rust monster is a creature of curious,
even comical appearance. It waddles with
great speed in an ungainly, rocking motion
like a raccoon cub, dubbed ?gallumphing?
by some long-ago observer, and chitters in
the fashion of field mice. It is much re-
spected by artisans and fighting-men, how-
ever, for its power to cause metal to rust or
corrode away by its touch, which corroded
metal it then devours and lives on. An
example of this respect is the great merce-
nary general Gulgathas, who has issued
standing orders that all smithies in his ar-
my?s encampments are to be encircled with
a bristling row of sloped, fire-hardened
stakes, or propped spears, to discourage the
attacks of such creatures.

Rust monsters are non-aggressive, but
are both curious and utterly fearless ?
even, it is said, being immune to magical
and psionic influence in their single-minded
pursuit of metal. (1) They can smell metal
from as far away as a man can make out the
features of another man, and are known to
prefer ferrous metals over non-ferrous
sorts. (2) Metal clearly visible to the eyes but
beyond smell range is apparently nonexis-
tent to rust monsters, and they climb poorly,
so the lofty upper reaches of any pole or tree
that can withstand their gallumphing
charges is a safe haven against the crea-
tures. They have near-infinite patience and
perseverance, however, and have been
known to wait at the base of such a nearby
trove for a month or more. (3)

Perhaps the best way of battling a rust
monster is to crush it in a deadfall, with
rolled boulders, or perhaps to trap it in a pit
and strike it from above with rocks and
clubs. If one must face it in open-field bat-
tle, it can often be successfully disabled by
first striking at its antennae and then at its
legs, possibly enabling one to escape with
prized metal (magical weapon, coins, jew-
elry) intact. Beware its tail ? an ankle-
high, lashing sweep of this appendage has
knocked many a warrior on his rump, and
before he can rise the creature has spun
about to beat upon his armor with its anten-
nae, and greedily seek out buckles, weap-
ons, flasks, coffers, and even mirrors buried
deep in backpacks! (4) It has a dexterous,
sticky, six-inch-long tongue that it can ex-
tend from under its beak to catch up even
the smallest flakes of metal or rust.

It is not known what rust monsters origi-
nally ate, or why they developed a bony
?shell? of armor, an oddly shaped tail, or
their strangely specialized antennae, but
since recorded history began these curious
beasts have lived in symbiosis with a partic-
ular type of bacteria that can apparently
coexist with no other species of creature.

These bacteria are found in a rust mon-
ster?s antennae, stomach, and bloodstream,
and have a particular need for metallic ores.
They gain energy from the sun (the monster
absorbs heat through its body armor and
tail), and with this and ingested metallic
oxides (more commonly called ?rust?), they
produce chemical energy (sugar) to power,
repair, and nourish for growth both them-
selves (the bacteria cells) and their host, the
rust monster.

The bacteria ? a type not yet identified
or reproduced by any alchemist ?  can
upon contact with any metal (there are no
known exceptions) oxidize the metal, (5)
even if it is inside a rust monster. Thus, anything
swallowed by a rust monster, touched by its
antennae or tongue, or that draws blood
from its innards will rust. A weapon that
bounces harmlessly off a rust monster?s tail,
legs, or bony shell will be unaffected, but
any metal weapon that pierces its bony shell
and wounds the beast will immediately rust
and become useless. Hand-held wooden
piercing weapons do not have enough
strength to penetrate the shell, and can only
harm-its eyes and mouth. Wooden clubs are
effective weapons against the beast, as are
crossbow bolts and arrows.

Rust monsters cannot dig through rock,
but can scratch away loose rubble and earth
to uncover buried metal (in tombs or
caches). They can glean sustenance from all
ferrous metallic ores, and often follow the
subterranean tunnels of umber hulks, pur-
ple worms, and the like, searching for ex-
posed veins of ore in the tunnel walls, or
metal treasure in the lairs of various under-
ground creatures. Many an otyugh has
dined on a rust monster that tried to root
through it to get at treasure lying under-
neath.

The beasts will often be found exploring
mines in search of tools and ironmongery.
In one mine north of Mirabar, a standing
guard of warriors with wooden weapons is
employed to keep lurking rust monsters
away from the exposed veins of ore, tools
and hoists, and quarried ore. Magic-users
are sometimes hired to rid a place of rust
monsters by the use of ?chain traps.?
Lengths of old, rusty chain are laid in a
large circle in a strategically located cavern
or other large area; at the center of the
circle sits the magic-user and a few body-
guards with wooden staves. When a rust
monster gallumphs up to feast, it ignores
the men, the magic-user leisurely throws a
fireball at the beast, and its body is rolled
aside with the staves. If scavengers (such as
hunting dogs or dungeon inhabitants) are
not likely to dispose of the remains, the
body is painted with a rune or message to
warn away other adventurers. Rust monster
antennae will continue to rust metal for
some time after the creature?s death. (6)

Rust monsters wander endlessly in search
of food, their bony exterior armor protect-
ing them from most predators. They do not
pair for life or choose specific mates, but
merely mate with another rust monster
when circumstances allow. This prolificacy
has kept the curiously unaggressive rust
monster from dying out in the face of at-
tacks from humans and natural predators. (7)

Notes

1. A rust monster has only  animal  intelli-
gence, and although it will choose to avoid
noise, light, and groups of other living
creatures, these cautious habits are swept
away when it smells a meal. It will pursue
edible metal that it has detected regardless
of attacks upon it, potential danger, or
attempts to  charm, dominate,  or otherwise
control its actions by magical or psionic
means. (This includes a  repulsion  spell, but
a  push  from a magic-user of sufficiently
high level would work. A  gust of wind,
however, will not even slow a hungry,
ground-hugging rust monster.) The beast?s
instinctive hunger for metal is too strong for
the monster?s dim intellect to even notice
any other forces attempting to coerce it. In
theory,  charm monster  could affect the beast
? but only if it is not commanded to do
anything that violates its basic nature. (In
other words, any command it is given must
directly involve getting something to eat, or
the  charm  is liable to be broken.) Psionic
domination  of a rust monster is also possi-
ble, but it can be troublesome and expen-
sive to maintain control of the monster
while forcing it to act against its nature.

2. The sense of smell of a rust monster is
apparently linked to magnetism; it increases
in effectiveness as the amount and purity of
the metal increases. Thus, traces of metal
immersed or suspended in liquid, sand, or
some forms of clay would escape the rust
monster?s attention; but rusty nails or tiny
shards of metal from a notched or scratched
weapon would not. The beast?s acute (effec-
tive up to 9" distant) sense of smell is be-
lieved to be a result of a strain of bacteria
unique to rust monsters, which also lends
them their rusting ability. Rust monsters
can also smell non-ferrous (non-magnetic)
metal, but only at a distance of 2?.

3. A rust monster can go for as long as
two months between one full meal (a suit of
plate mail, or equivalent weight in metal)
and the next, if it does not expend much
energy in the meantime. The monster will
unthinkingly try to wait out a target
perched in a tree, but won?t wait so long
that it starves to death. (The unfortunate
figure in the tree will probably fall uncon-
scious and drop out of the tree long before
this anyway.)

4. If the die roll for the rust monster?s
chance to hit is one or two digits lower than
the number needed for a successful strike
with its antennae, there is a chance that it
has knocked over an adversary with its tail.
Any humanoid standing to the rear of the
monster or on either side of it within 5 feet
of its body must roll his dexterity or lower
on d20 to avoid being knocked down by a
sweep of the tail. The rust monster is +4 to
hit in the following round against any single
target that was knocked down; a miss indi-
cates that the character managed to scram-
ble to his feet and get out of reach of the
antennae in time. No character who is
knocked down can attack the rust monster
in the following round.

The DM should judge the effects of a
successful rust monster antenna-strike ac-
cording to the circumstances. If only a
certain part of a character?s body or weapon
is exposed through a doorway or hole, then
only that part can be affected. However, the
rust does spread across the extent of an
entire area of metal; if a character clad in a
ring mail jersey strikes at a rust monster
through a small opening and his arm is hit
by one of the antennae, the  rust will travel
along the jersey and the character will soon
lose his shirt. The corrosive action does not
?jump? across gaps between two objects or
areas of metal. For instance, a character
who wears metal leggings and a metal
breastplate that aren?t in contact with each
other will not have all of his armor affected
by the same strike, in the same way that a
suit of armor and a helm cannot be rusted
at the same time ? unless there is a metal-
to-metal connection between the armor and
the helm.

Obviously, the item struck will only be
affected if it is being held, carried, or worn
by the target, and only if the item is metal.
Re-roll if an effect on an absent or non-
metallic item is indicated, or simply assign a
result if only one of the above items is appli-
cable. The rust monster never fails to rust
something  on a successful hit, as long as the
target is wearing or carrying anything
metallic in plain view. If the target charac-
ter or creature has no metal to be rusted,
there can?t be a successful hit in the first
place. Even so, the rust monster will smell
metal items in a backpack or belt pouch,
and will relentlessly try to get at the metal it
cannot see unless and until a better prospect
comes along.

Metal gates, statues (even animated,
magical ones such as iron golems) and the
like can be affected by rust monster anten-
nae strikes. Very large objects may take 1 or
2 rounds before rusting entirely and then
collapsing. Magical objects with a ?plus?
get a straight saving throw, at 10% per
?plus,? to avoid being rusted, as per the <description of the rust monster in>
Monster Manual. Large enchanted objects
(such as an iron golem) get a saving throw
vs. petrification at +1 to avoid the rusting
effect. An iron golem striking a rust mon-
ster would do 4-40 points of damage, per-
haps killing the creature ? but if a golem
carrying an edged weapon struck the anten-
nae or the body of the rust monster with its
blade and not with a crushing blow from its
fist (the golem is unintelligent and does not
choose its attack mode deliberately), the
golem would begin to corrode immediately
and would collapse into a mound of rust at
the end of the following round. During this
second round, it can move only 3" without
toppling, and it will do only half damage on
any attack.

A rust monster antenna will take at least
5 HP of damage before being severed.
Rust monsters are apparently immune to all
forms of poison, including the breath weap-
ons of iron golems and those of brass,
bronze, silver, green, and gold dragons
(who must often fight rust monsters to
defend their hoards), and liquid poisons
produced by various creatures and by men
(and smeared on weapons). Fire does nor-
mal damage to a rust monster, but acid
rarely seems to have an effect (+3 on saving
throw, half damage if save fails, no damage
if save succeeds).

6. The bacteria can survive, and continue
to act through the antennae, for 6-105 days
after the death of the host rust monster,
depending on the availability of food. The
bacteria can thrive on previously devoured
metallic oxides in the stomach and blood-
stream of the monster, any metallic weapons
left lodged in the monster?s body, or newly
introduced metal ? but the bacteria will die
when such supplies are exhausted. A rust
monster antenna that was placed in a bowl
of water with rust and a lot of metal could
continue to thrive indefinitely, and perhaps
could even be carried as a weapon for occa-
sions of 5 days or less before the bacteria
would need to have their food supply re-
plenished.

A scavenger that devours a rust monster
would have any previously devoured metal-
lic treasure still in its body rusted and eaten
by the bacteria, but the bacteria could  not
take over the creature so that its attacks
would have the ability to rust. Only the
creature known as the rust monster (sages
have argued over a ?proper? name for this
beast for decades, but none has gained
common acceptance, or seems likely to) can
support the mysterious bacteria, and rust
monsters do not eat each other. In the ex-
ample of the scavenger mentioned above,
the bacteria would die when its metallic
food in the scavenger?s stomach was used
up, without harming the host, and would be
excreted.

7. Rust monsters mate often, following a
ritual in which each one of the pair makes
agitated chittering noises for several min-
utes. If one of the adults is fertilized, a
young rust monster will begin to form in the
body of the parent. It will be born 4-7
months later, live, whole, and active, and
will usually accompany its parent until it is
full grown.

Newly born rust monsters have all the
powers of an adult (there is a transferal of
some of the bacteria from parent to child),
but have only 1+4 HD and are size S, with a
5-foot-long tail and 3-foot-long antennae.
Such a "rusty" will grow rapidly to a
young, 3 HD, M-size form, with full adult-
size tail (10') and antennae (7'), usually
within 8 months or so, but this growth is
dependent on food supply. After a year of
life a rust monster is a mature adult and can
mate with others of its kind.

-
Rustbusters
-
Dear editor:
In "The ecology of the rust monster" (issue
#88) there are a few errors. The Monster Manual
states that they inhabit and roam only dark
subterranean places. The article states that
Gulgathas issued orders that all smithies in his
major encampments are to be encircled with
sloped stakes or spears to discourage the attacks
of such creatures. But such monsters are not
supposed to be there in the first place.

Since the article states (or suggests) that they
do, it would be a safe assumption to say that rust
monsters might roam open areas at night when
there is not much going on and no light. Or, that
they might come out in search for more or better
metals. This point might help to clarify the
article.
John H. Cantrell II
Jeffersonville, Ga.
(Dragon #91)
 

Dear Dragon:
In issue #88 I found what appears to be an
error in the text. This error is evident on the
article describing the rust monster. In the
"Notes" section of this article, under captions
two and five, there were two statements in which
the ", or inches, sign was used. I feel that the
author meant to use the ', or feet, sign instead. Is
my assumption correct?

William Blandford
Wallingford, Pa.
(Dragon #91)


Dear editor:
There are a few questions raised by "The
ecology of the rust monster" and a few old unasked
questions concerning the rust monster and
its attacks. They are: Do any metal objects get a
saving throw against the rust monster's effects?
Does a magic bonus add to this save? If a rust
monster's blood is collected and bottled, will the
bacteria still be active? (If so, adventurers will try
this to make good missile weapons to easily
destroy enemy armor and weapons.) Finally, can
a magic-user isolate the bacteria to make a rusting
potion?

Robert J. Watson
Rhinelander, Wis.
(Dragon #91)
 

The rust monster article didn’t make the
specific point that the creatures might be encountered
outside a dungeon, but the example of
Gulgathas does imply that such things happen.
John is correct in pointing out something that
might have confused readers, and the idea of rust
monsters roaming open ground could have been
explored in the article. The MM cites a “% in
lair” figure of 10% for the rust monster, implying
that it doesn’t stay home much, and that makes
sense considering its dietary habits. Carry that
reasoning a little further, and it’s not hard to
imagine a rust monster foraging outdoors at night
— especially if no decent meals have wandered
down into the dungeon lately. We can assume
that the monster has some kind of a homing
instinct that enables it to find the dungeon entrance
(and its lair) again after an excursion into
the outside world. Or, it might stray too far in
pursuit of a tasty suit of armor and go beyond the
range of the homing instinct, in which case other
instincts would lead it to search around for a new
home — a nearby cave, perhaps, or how about
that tunnel that leads into the castle basement?

The problem with the “inch” marks is not a
problem. Assuming we’re using underground
scale (1 scale “inch” = 10 feet), the monster’s
sense of smell has a range of 90 feet (not 9 feet, as
William suggests), and a range of 20 feet when
detecting non-ferrous metals. The golem moves
at half speed on the second round after being
rusted — 3”, or 30 feet, per round instead of its
normal 6” movement rate.

In outdoor scale, where 1 “inch” = 10 yards,
the golem’s movement rate is changed accordingly:
60 yards per round normally, 30 yards per
round after being rusted. However, we recommend
that you keep the rust monster’s sense-ofsmell
range at 90 (or 20) feet outdoors instead of
increasing it to 90 (or 20) yards. In the same way
that a spell’s area of effect is always measured as
1”= 10 feet, the “area of effect” of a rust monster’s
nose should always be the same quantity
regardless of which scale applies.

Robert’s questions can all be answered by
examining the article. Non-magical metal items
don’t get a saving throw against the rust monster’s
attack, but even in the worst of cases the
monster’s attack isn‘t a sure thing. The only way
a metal item can “save” against a rust monster’s
strike is for the rust monster to fail its roll to hit.
A stationary, “defenseless” hunk of metal would
be AC 10 for purposes of determining whether
the monster hits. A creature of 5 HD has an 80% 
chance of hitting AC 10, which means that the 
target has a 20% chance of not being rusted by 
any particular attack. 

As pointed out in the article and in the Monster
Manual description, magical items do get a
saving throw — in many circumstances, at least.
If the item (usually armor or weaponry) is enchanted
to +1 or higher, it gets a saving throw of
10% per “plus.” In other words, a +1 sword gets
a saving throw of 19 (giving a 10% chance of
rolling either a 19 or 20); a +3 sword gets a saving
throw of 15; and a + 5 sword gets a saving throw
of 11. Magical items without a “‘plus” rating get
no saving throw at all, but the DM might want to
overrule this in a special case.

Note 6 makes it pretty clear that the bacteria
inside the rust monster will not survive outside
the monster’s body This would make it impossible
to bottle rust monster blood and use it as an
effective missile weapon, and very difficult (at
best) for anyone to concoct a rusting potion using
the bacteria.

— KM
(Dragon #91)