PDA

View Full Version : [4e] Rust Monster



Guinea Anubis
2009-11-18, 11:51 AM
So unless I some how missed it in MM1 and MM2 there still is no Rust Monster for 4e. But since I am not up on all the adventures that have been released I was wondering if it happened to be in any of them.

AllisterH
2009-11-18, 11:52 AM
There's a rust monster in the MM2

Mando Knight
2009-11-18, 11:53 AM
MM2. Look again: Rust Monster, Young Rust Monster Swarm, and Dweomer Eater, along with the RM Lodestone, RM Terror, and RM Nightmare in Dragon 376.

Guinea Anubis
2009-11-18, 11:58 AM
thanks, I'm stupid.

dsmiles
2009-11-18, 01:00 PM
Rust monsters rule...too bad I can't have one for a pet.

Person_Man
2009-11-18, 01:52 PM
Out of curiosity, do Rush Monsters destroy enchanted items? 4E has a reflexive phobia against "punishing players" - making death extremely rare, removing permanent penalties, etc. I'm not passing judgment on whether or not this is a good thing. But given the general thrust of 4E mechanics, I assumed they would just leave the Rust Monster out, or nerf it to such a degree that it's pointless.

kc0bbq
2009-11-18, 01:54 PM
Yes they do destroy enchanted items. Once you kill them there is residuum in their belly because they can't digest the magic.

dsmiles
2009-11-18, 01:59 PM
Out of curiosity, do Rush Monsters destroy enchanted items? 4E has a reflexive phobia against "punishing players" - making death extremely rare, removing permanent penalties, etc. I'm not passing judgment on whether or not this is a good thing. But given the general thrust of 4E mechanics, I assumed they would just leave the Rust Monster out, or nerf it to such a degree that it's pointless.

Yeah, some of those rules are homebrewed at my table. Death is not rare. If you run out of HP, you are incap, you hit -10 you die instantly (no kidding).
And I continue to punish players, but I still only punish players for being stupid. If someone tries to kick in a door (literally, that is) without looking at it first, the door pulls open instead of pushes, you may just break you leg trying it.

SpikeFightwicky
2009-11-18, 01:59 PM
Out of curiosity, do Rush Monsters destroy enchanted items? [snip!]

Only if you can't distract them with Tom Sawyer.

I've found that 'destroys your item' monsters are never popular with my group. Be it a rust monster or some kind of ooze, the tears fall when magic and adamantium weapons start to corrode. Not only that, but assuming wealth (or, magic items) by level, it's a quick way to neutralize the melee types. I had some players in a game I ran carrying clubs and jade axes specifically to counter rust monsters and oozes (they never did encounter them again, though...)

jmbrown
2009-11-18, 02:27 PM
Yes they do destroy enchanted items. Once you kill them there is residuum in their belly because they can't digest the magic.

In addition, just in case someone pops in here and points out how easily this is broken, there's a specific note by the rust monster which states the DM has every right to put his foot down if the players abuse this. A rust monster is, in effect, a free full powered disenchant. If a player abuses this fact by purposefully feeding a rust monster unwanted magic in order to get full priced residuum, the DM should instead give them the normal 1/5th value.

Person_Man
2009-11-18, 02:58 PM
In addition, just in case someone pops in here and points out how easily this is broken, there's a specific note by the rust monster which states the DM has every right to put his foot down if the players abuse this. A rust monster is, in effect, a free full powered disenchant. If a player abuses this fact by purposefully feeding a rust monster unwanted magic in order to get full priced residuum, the DM should instead give them the normal 1/5th value.

Wait, I'm confused.


Rust Monsters can easily eat/destroy metal items, including magic items.
However, they can't digest magic. So your magic items are essentially converted to gp (in the form of residuum), which you can recover by killing them or following them around until they poo.
Therefore, fighting a Rust Monster basically just inconveniences you until the next time you go to a town. And in some regards they're helpful, because you can trade in unused/lower level/weak magic items for gp without the markdown.
Realizing that this would be a helpful loophole for PCs, the MMII specifically tells DMs not to let PCs use it, and to change the rules if they do.


Right?

Feel free to flame me if you think I'm wrong, but that seems a bit backasswards. Either they should have Rust Monsters, and trust that DMs can always replace treasure by having PCs find/win/capture more stuff - perhaps explicitly telling him in the Rust Monster's description that PCs hate having their stuff destroyed, and that they should be careful about how they handle it. Or they should not have a Rust Monster. Or they could have a Rust monster but limit it so that it can't destroy magic items. Or they should just have people who capture/breed Rust Monsters for the specific purpose of using them to convert unwanted magic items to residuum (I can totally see that as a normal part of Eberron, btw).

But creating a rule, and then telling DMs to change it if the PCs recognize what it can be used for, completely destroys any "world simulation" and/or versimilitute left in D&D.

kc0bbq
2009-11-18, 03:01 PM
But creating a rule, and then telling DMs to change it if the PCs recognize what it can be used for, completely destroys any "world simulation" and/or versimilitute left in D&D.What's confusing about taking the most annoying monster ever, designed to annoy and or ruin characters and taking a bit of the sting out of it, but warning the DM to not let the players circumvent the economy?

It's an elegant solution.

Necron
2009-11-18, 03:04 PM
Hrmmm... note to self... tame a rust monster for breaking down useless magic items... =)

Hzurr
2009-11-18, 03:34 PM
It's an elegant solution. For a more civilized age...

Another_Poet
2009-11-18, 03:34 PM
I don't have MM2 so I'm not sure but:

Do you have to kill it to get the residuum?

If you can't just wait for it to poop, then most of the problem is solved. Feeding it something and getting the residuum is a one-shot deal.

nightwyrm
2009-11-18, 03:45 PM
It's not that RM can't digest magic. It's that it takes awhile for them to digest it. So if the RM eats your sword and then you kill it, you get your residuum back, but if you let it go sleep off its big meal, you get nothing for your sword.

There's a whole freaking article about RM farming and why it's a bad idea in one of the Dragon mags.

HMS Invincible
2009-11-18, 04:15 PM
The answer to rust monsters being used to get full value out of items is the same answer to PC's robbing merchants, trading with other adventurers, and all other attempts to circumvent the wealth by level tables.
Make it an adventure.
Where are the rust monsters prevalent? Are they so rare that they need to consult multiple sages who charge fees or ask for favors?
How far away is it and how many dangers do they face before they finally meet a rust monster? What if the PC's get swarmed by rust monsters and forced to retreat without retrieving residium?

Yakk
2009-11-18, 04:17 PM
Wait, I'm confused.


Rust Monsters can easily eat/destroy metal items, including magic items.
However, they can't digest magic. So your magic items are essentially converted to gp (in the form of residuum), which you can recover by killing them or following them around until they poo.
Actually, they digest magic at a rate that is hard to predict, but usually not fast enough that if you kill them within minutes of them eating the material. Usually.

Right?

Feel free to flame me if you think I'm wrong, but that seems a bit backasswards. Either they should have Rust Monsters, and trust that DMs can always replace treasure by having PCs find/win/capture more stuff
This actually increases the amount of effort that the DM has to go through. It also leads to the weird situation where treasure gained later on is a function of treasure lost during the Rust Monster encounter.

- perhaps explicitly telling him in the Rust Monster's description that PCs hate having their stuff destroyed, and that they should be careful about how they handle. Or they should not have a Rust Monster. Or they could have a Rust monster but limit it so that it can't destroy magic items.
Sure.

Or they should just have people who capture/breed Rust Monsters for the specific purpose of using them to convert unwanted magic items to residuum (I can totally see that as a normal part of Eberron, btw).
But they want a Rust Monster that destroys magic items, but (by default) doesn't require a bunch of extra effort for the DM to account for the magic items destroyed and compensate the players for them.

At the same time, they don't want Rust Monster farming -- so Rust Monsters respond poorly to domestication, and harvesting residuum from a Rust Monster is not guaranteed.

Rust Monsters are not domesticated creatures of disenchantment -- they are annoyances. There are justifications why, but these reasons are not important if you interact with them as annoyances (ie, encounters). If you try to interact with them as domesticated animals, then the problems that make Rust Monsters not appropriate for this reason start to matter.

Having the "these aren't domesticated animals" features leak into their "these are monsters in an encounter" would needlessly complicate the encounter statistics of the Rust monster, which are kept simple so they are easy to run and use for the DM. Because that is important (really).

They want a simple to use monster for an encounter that is a Rust Monster, which destroys items.

This monster is not intended (by default) to be a domesticated tool. The reasons why it doesn't work as a tool are not important in the context of the battle with the rust monster, and are dealt with (like most out of combat things in 4e) by the DM being a better world simulator than the combat rules are.

Dusk Eclipse
2009-11-18, 04:55 PM
umm what is this residium you are all taking about? My group only have access to 4E Core (PHB, DMG & MM1) and my DM is the one who owns it.
Besides we don't play 4E that much

Mando Knight
2009-11-18, 05:09 PM
umm what is this residium you are all taking about?

Residuum (as defined by the game): The concentrated magical substance that results from using the Disenchant Magic Item ritual, residuum can be used as a component for any ritual.

Residuum (somewhat laconic): Shiny stuff that's made of magic. Lets you do things with rituals without bothering with bookkeeping for specific components.

Dusk Eclipse
2009-11-18, 05:35 PM
Oh, now that makes much more sense

KillianHawkeye
2009-11-18, 07:12 PM
And of course, the point of the rust monster containing residuum is so that the PCs can use it for the Enchant Item ritual needed to restore their lost equipment.

jmbrown
2009-11-18, 07:17 PM
And of course, the point of the rust monster containing residuum is so that the PCs can use it for the Enchant Item ritual needed to restore their lost equipment.

Yes, and like I mentioned the MM2 expressly warns DM's that players may abuse the monster by intentionally feeding it unwanted magic items instead of selling them.

It's not a rule but a precautionary statement. If the DMG for 3.5 contained a note saying "Players may abuse traps by creating infinite item creation traps with an automatic reset" it wouldn't ruin the rules as presented. If it exists, it can be abused and like everything in D&D the DM has the final say.

If players lose their favorite sword in a harrowing fight, they should be able to find the full residuum in the monster's belly. If the players drop random, low level magic items to lure the monster in a trap then they should only find 1/5 the value which is what you'd get if you sold or disenchanted it.

The New Bruceski
2009-11-18, 07:24 PM
Or to put it another way, "This creature screws with the players in ways its attack stats don't make obvious. If you use one, REALIZE you're screwing with the players, and act accordingly."

SSGoW
2009-11-18, 07:59 PM
hmmm about having one as a pet... you could easily have one with a hole in its stomach like they do with cows to test them... the hole is able to be opened up so you can reach in and get the residium hmmm

KillianHawkeye
2009-11-18, 08:14 PM
Yes, and like I mentioned the MM2 expressly warns DM's that players may abuse the monster by intentionally feeding it unwanted magic items instead of selling them.

It's not a rule but a precautionary statement. If the DMG for 3.5 contained a note saying "Players may abuse traps by creating infinite item creation traps with an automatic reset" it wouldn't ruin the rules as presented. If it exists, it can be abused and like everything in D&D the DM has the final say.

If players lose their favorite sword in a harrowing fight, they should be able to find the full residuum in the monster's belly. If the players drop random, low level magic items to lure the monster in a trap then they should only find 1/5 the value which is what you'd get if you sold or disenchanted it.

Yes, I know. My comment was directed toward the fellow who didn't know what residuum was. I did read the whole thread.

jmbrown
2009-11-18, 08:15 PM
hmmm about having one as a pet... you could easily have one with a hole in its stomach like they do with cows to test them... the hole is able to be opened up so you can reach in and get the residium hmmm

As an aside, rust monsters in 4E are actually dangerous. Unlike 3E's rust monster, 4E's will feast on your innards while they're waiting for the metal to dissolve. Not only do their antennae dissolve metal but so does their bite and even their shell! They're stronger, tougher, meaner versions than 3E's aggressive but otherwise physically harmless monster.

Just saying that tying one up and putting a hole in an aberrant beast probably isn't going to work.

AshDesert
2009-11-18, 09:23 PM
Only if you can't distract them with Tom Sawyer.

I c wat u did there:smallbiggrin:

Anyways, I've always felt like the "destroy your stuff" monsters are only fun for the DM, so I don't mind them taking some of the sting out of the Rust Monster.

Moff Chumley
2009-11-18, 09:59 PM
What's wrong with the DM having fun? :smallbiggrin:

toddex
2009-11-18, 10:03 PM
Yeah, some of those rules are homebrewed at my table. Death is not rare. If you run out of HP, you are incap, you hit -10 you die instantly (no kidding).
And I continue to punish players, but I still only punish players for being stupid. If someone tries to kick in a door (literally, that is) without looking at it first, the door pulls open instead of pushes, you may just break you leg trying it.

That is some of the worst DMing ive ever read....

Mando Knight
2009-11-18, 10:07 PM
And I continue to punish players, but I still only punish players for being stupid. If someone tries to kick in a door (literally, that is) without looking at it first, the door pulls open instead of pushes, you may just break you leg trying it.

So the big Fighter guy with 16 Con and 20-ish Str is going to break his own body trying to knock down a door? When he's probably going to be able to tell before he reaches that point whether or not he's going to hurt himself? A little scrawny wizard-guy, sure, but the Fighter's supposed to be tough.

Thajocoth
2009-11-18, 10:59 PM
A single rust monster can only destroy a single magic item though, and it explicitly says they leave the residuum behind when they die, so I don't see the issue. If the players are going to abuse it, then they need to have carried around a magic item they don't want hoping to find a rust monster... Which is the best way to ensure none exist in their path. I don't see how it's farmable... Unless the PCs can somehow summon them...

Sir Homeslice
2009-11-18, 11:09 PM
So the big Fighter guy with 16 Con and 20-ish Str is going to break his own body trying to knock down a door? When he's probably going to be able to tell before he reaches that point whether or not he's going to hurt himself? A little scrawny wizard-guy, sure, but the Fighter's supposed to be tough.

Actually, unless you have a hideously weak bone structure, or are using an unnessecary amount of force against something like a thicks teel door, kicking a door, regardless of push/pull won't break your leg.

MCerberus
2009-11-18, 11:12 PM
Killing some catgirls here, kicking the door would put the force reacting to your body traveling up your leg from the foot, and it'll take a HELL of a lot of force to break a bone that way. The first thing to break would be the hinges.

jmbrown
2009-11-19, 04:33 AM
A single rust monster can only destroy a single magic item though, and it explicitly says they leave the residuum behind when they die, so I don't see the issue. If the players are going to abuse it, then they need to have carried around a magic item they don't want hoping to find a rust monster... Which is the best way to ensure none exist in their path. I don't see how it's farmable... Unless the PCs can somehow summon them...

Per encounter and rust monsters can only affect heavy armor and weapons that hit them so it's not like they can ruin your metal boots or magic helmet.

However, the PHB states that encounter powers outside of combat have a duration of 5 minutes and the monster manuals don't take into account world building. I think it's perfectly reasonable to assume it takes a rust monster 5 minutes to eat a common metal item. In battle they can only eat 1 item and while I've never had to deal with this I think it's a good ruling that if the players run and encounter the same rust monster who eats another item then they should find the full residuum for the new item and 1/5 for the last one.

Kurald Galain
2009-11-19, 04:44 AM
But creating a rule, and then telling DMs to change it if the PCs recognize what it can be used for, completely destroys any "world simulation" and/or versimilitute left in D&D.
Well, it is the gamist approach. A design principle for 4E is that penalties aren't fun, so an attack that would e.g. destroy your armor instead gives you a -2 to AC (save ends).

Come to think of it, it would be fun to have the 4E designers play Dwarf Fortress for awhile :smallbiggrin:

Kurald Galain
2009-11-19, 04:46 AM
So the big Fighter guy with 16 Con and 20-ish Str is going to break his own body trying to knock down a door?

Sure! And whenever you roll a natural one on an attack roll, you stab yourself for critical damage! It's realistic and happened all the time in the medieval ages! /sarcasm

dsmiles
2009-11-19, 05:46 AM
Yes, and like I mentioned the MM2 expressly warns DM's that players may abuse the monster by intentionally feeding it unwanted magic items instead of selling them.

It's not a rule but a precautionary statement. If the DMG for 3.5 contained a note saying "Players may abuse traps by creating infinite item creation traps with an automatic reset" it wouldn't ruin the rules as presented. If it exists, it can be abused and like everything in D&D the DM has the final say.

If players lose their favorite sword in a harrowing fight, they should be able to find the full residuum in the monster's belly. If the players drop random, low level magic items to lure the monster in a trap then they should only find 1/5 the value which is what you'd get if you sold or disenchanted it.

Or nothing, for being pogues.

SpikeFightwicky
2009-11-19, 07:37 AM
I c wat u did there:smallbiggrin:

Anyways, I've always felt like the "destroy your stuff" monsters are only fun for the DM, so I don't mind them taking some of the sting out of the Rust Monster.

Heh, glad somebody did. I was worried it was too obscure, but it seems to have gotten its time in the Limelight :smallwink:

How often do people use rust monsters or other monsters that 'eat' PC equipment (like oozes in 3.5. Not sure how they work in 4E)? I stopped using rust monsters and black oozes because of the negative material acquisitions they provide. It was the one monster that the players have never enjoyed. The only other monster I can think of is the Bodak. That monster's designed for the sole purpose of PC death at low levels. Though at least he gets to the point, unlike the Rust Monster (leaving the adventurers equipmentless and embarassed).

unre9istered
2009-11-19, 08:50 AM
I've decided that rust monsters don't just have the full residuum value in their bellies. They have the normal 1/5 residuum and chucks of partially enchanted rust that can be used (with the residuum) to re-create the item that was destroyed.
Now it's a normal strength DE with the option of full recovery of the item.
I honestly don't know why WotC didn't do it that way in the first place.

Renchard
2009-11-19, 09:00 AM
I've decided that rust monsters don't just have the full residuum value in their bellies. They have the normal 1/5 residuum and chucks of partially enchanted rust that can be used (with the residuum) to re-create the item that was destroyed.
Now it's a normal strength DE with the option of full recovery of the item.
I honestly don't know why WotC didn't do it that way in the first place.
You know, that's pretty awesome. Consider it stolen.

Guinea Anubis
2009-11-19, 09:18 AM
I've decided that rust monsters don't just have the full residuum value in their bellies. They have the normal 1/5 residuum and chucks of partially enchanted rust that can be used (with the residuum) to re-create the item that was destroyed.
Now it's a normal strength DE with the option of full recovery of the item.
I honestly don't know why WotC didn't do it that way in the first place.

I like this idea I am going to steal it too.

Person_Man
2009-11-19, 09:54 AM
As an aside, rust monsters in 4E are actually dangerous. Unlike 3E's rust monster, 4E's will feast on your innards while they're waiting for the metal to dissolve. Not only do their antennae dissolve metal but so does their bite and even their shell! They're stronger, tougher, meaner versions than 3E's aggressive but otherwise physically harmless monster.

Just saying that tying one up and putting a hole in an aberrant beast probably isn't going to work.

Wait, what? So their entire body is covered in digestive fluid?

Anywho, props to unre9istered for what seems like the most intelligent response. If I ever use a Rust Monster, think I will steal that as well.

And for the record I like that 4E took a Gamist approach, and that they're sticking with it. I just wish they put more time into making the crunch "rationally" consistent. Just saying that your game doesn't focus on world building isn't an excuse for lazy writing.

Guinea Anubis
2009-11-19, 10:33 AM
IIRC rust monsters just have to touch an item to make it rust, then they eat the rust.

I am a little sad to see that the rusting it does to armor and weapons only lasts untill the end of the encounter. Also a little bit of a let down that it can only eat 1 item per encounter. It feels like there is not much to fear from the rust monsters any more.

jmbrown
2009-11-19, 10:47 AM
I've decided that rust monsters don't just have the full residuum value in their bellies. They have the normal 1/5 residuum and chucks of partially enchanted rust that can be used (with the residuum) to re-create the item that was destroyed.
Now it's a normal strength DE with the option of full recovery of the item.
I honestly don't know why WotC didn't do it that way in the first place.

Extra junk the DM and players has to keep track of. Aside from powers, one of the goals for 4E was little book keeping. This is why rituals use liquid resources instead of intricate components and multiple foci.

Not that I'm saying it's a bad idea, because it isn't (it's not like players can sell rusted hafts and axe heads), but it's an extra line the players have to write down "so and so residuum; chunks of rusted item" It's easier just to say "Full value of item destroyed."


How often do people use rust monsters or other monsters that 'eat' PC equipment (like oozes in 3.5. Not sure how they work in 4E)?

Never. It's the one aspect of the 'Gygaxian' era I've never been fond of. There are better ways to screw with the players but destroying their hard earned equipment through any other method that isn't their own negligence is really, really bad design IMO.


Wait, what? So their entire body is covered in digestive fluid?

Essentially, yes. You strike them with a metal weapon and it has the "rusting" property.

Tiki Snakes
2009-11-19, 10:53 AM
IIRC rust monsters just have to touch an item to make it rust, then they eat the rust.

I am a little sad to see that the rusting it does to armor and weapons only lasts untill the end of the encounter. Also a little bit of a let down that it can only eat 1 item per encounter. It feels like there is not much to fear from the rust monsters any more.

A Rust monster is a non-elite, non solo creature. Generally, a group of 5 pc's can expect to either encounter one in a group of other monsters, in which case it provides a dangerous additional concern, or they will encounter 5 or more of them at once.

There is a Solo Rust Monster, level 24. It's pretty handy. It's magic-item-eating schtick recharges on a five or six, so it's likely to use it several times. Similar for the Dweomer Eater rust monster, whose ability recharges on a six, but is only a standard monster. So expect several of them.

Generally, items will be lost, likely in quite respectable quantities if the rusties go full out. I could quite conceivably see a lucky party of Dweomer Eaters taking out between 5 and 9 magic items in a single encounter.

Gralamin
2009-11-19, 11:10 AM
I've decided that rust monsters don't just have the full residuum value in their bellies. They have the normal 1/5 residuum and chucks of partially enchanted rust that can be used (with the residuum) to re-create the item that was destroyed.
Now it's a normal strength DE with the option of full recovery of the item.
I honestly don't know why WotC didn't do it that way in the first place.

As said by a lot of others: Stolen.

Person_Man
2009-11-19, 11:33 AM
A Rust monster is a non-elite, non solo creature. Generally, a group of 5 pc's can expect to either encounter one in a group of other monsters, in which case it provides a dangerous additional concern, or they will encounter 5 or more of them at once.


Out of curiosity, do people actually group dissimilar monsters together if there is no fluff reason to do so? From a Gamist perspective it would make sense, because it mixes up the tactical challenges the PCs must face in a single combat. But from a fluff perspective, I just can't see a Rust Monster just randomly accompanying other monsters unless it was being kept as a pet/guard dog, which is already ruled out by it's fluff.

Kurald Galain
2009-11-19, 11:39 AM
Out of curiosity, do people actually group dissimilar monsters together if there is no fluff reason to do so?
I'm sure those people exist.

Regardless, the monster manual suggests a few groups for all non-solo monsters. For instance, it would (hypothetically, since I'm AFB) suggest that a rust monster is found in a swarm of three accompanied by a rust cleric and a groundworm, or that five kobolds and a draco-caster would have a Master Corroder Rust Monster as their mount. Or something like that, anyway.

jmbrown
2009-11-19, 11:53 AM
Out of curiosity, do people actually group dissimilar monsters together if there is no fluff reason to do so? From a Gamist perspective it would make sense, because it mixes up the tactical challenges the PCs must face in a single combat. But from a fluff perspective, I just can't see a Rust Monster just randomly accompanying other monsters unless it was being kept as a pet/guard dog, which is already ruled out by it's fluff.

The MMs suggest pairings for monsters but they're actually accurate to the fluff provided. It's difficult to pair up rust monsters with intelligent creatures because they're hard to control and go after any metal but the example in MM2 suggests a party will likely encounter them in a situation that will attract another underground dwelling predator that find the PCs a better meal than the individual rust monster.

Artanis
2009-11-19, 11:53 AM
Maybe the PCs run into somebody using Rust Monsters to farm residuum :smalltongue:

Mando Knight
2009-11-19, 11:57 AM
IIRC rust monsters just have to touch an item to make it rust, then they eat the rust.

I am a little sad to see that the rusting it does to armor and weapons only lasts untill the end of the encounter. Also a little bit of a let down that it can only eat 1 item per encounter. It feels like there is not much to fear from the rust monsters any more.

The rusting effect of the monster is about as powerful as its rust-eating ability: you're taking cumulative hits to your defenses or offenses as the battle goes on, even if it's already eaten its one item per encounter.

Yakk
2009-11-19, 01:43 PM
I've decided that rust monsters don't just have the full residuum value in their bellies. They have the normal 1/5 residuum and chucks of partially enchanted rust that can be used (with the residuum) to re-create the item that was destroyed.
Now it's a normal strength DE with the option of full recovery of the item.
I honestly don't know why WotC didn't do it that way in the first place.
Neat. That is similar to the 'template' idea I had to get rid of magic item shops, yet leave players with lots of choice.

You'd get both residuum and typed magic item materials and templates.

A template is an item that lets you make items that are 'beyond' your character level, and contributes to making them cheaper.

In order to make a magic item, at least half of the magic item materials have to have appropriate adjectives. So you might find adamandium (which is magical metal), or the gizzard of a red dragon (which has the adjective fire). Then using some random magical materials, some red dragon gizzard, some adamantium, you could create a magic flaming sword (metal, fire) -- but the random stuff would have to be no more than half of it.

You might also find that the tooth of the red dragon makes a template for a magic sword, that lets you make a level 14 flaming sword at half cost.

In this case, we'd have the gizzard of the rust monster being a 80% template for the lost magic item, and it contains 20% typed residuum appropriate for the source magic item.

Naturally, the general system isn't needed for the specific case of the rust monster. (it just provides a way to give the party a +4 holy avenger, without having to justify the fact that the monsters they are fighting have a +4 holy avenger).