Thuldanin, Echoes of Avalas

'My name is Ozymandias, King of Kings!
Look upon my works, ye mighty, and despair!'
Nothing beside remains."

The great dump

Teleportation circle

## Acheron: In the Shadow of Wars Past

My ancestors went to war with their fists when they first met the elves, imbued with the magic of their shamans; they would brawl with each other, the blood of their enemy splattered on the ground. I go to war with the hobgoblins with swords and shields, with the blessings of my priests on my back; I slash through skin and guts, and stain my weapons with their blood. My descendants will go to war with some great iron machine, and see some great arcane power fly into the swaths of some unknown race; they will see fire and blood, erupting from their enemy, and burning on the ground. No matter the tools, no matter the enemy war never changes.
But after all of these wars have passed, the victor was left alone. Their general moved on to a new village. Their family fears what they have become. Their fists were worn raw, their swords are rusted, their great war machines will collapse, purposeless. Bards will tell stories of great conflicts and epic leaders, but no one will ever know what sacrifice my ancestors, myself, my descendants, will make. Not until some lost soul stumbles through the wilderness where the great cities besieged once stood, to find some monumental fragment. They stop to guess, just as I do of ages past for me, what powerful but unrecorded race once dwelt in this annihilated place. And what immense force annihilated.
But while they may wonder the exact details, in their hearts they will know. Even they will know war. And war... war never changes.

Between the fires of Hell and the order of Nirvana, the souls of the war-mongers and the willing soldiers awake for their eternal afterlives in Avalas, the first layer of Acheron. These are lawful evil souls deemed unworthy of Mechanus, yet unworthy of Baator as well.

These souls will wage war forever, ever brutalized and brutalizing, in and endless cycle of war, death, and dark rebirth, as they are claimed by the evil gods of war. However, not all share this fate; some souls lay unclaimed by the gods of Avalas; these poor souls awake in Thuldanin, the Echoes of Avalas.

In this world, the wars are all over. The only things left here are dust, iron, and the rusted remains of the great battles which took place long ago. The rubble of iron fortresses, the broken parts of infernal war machines, the broken swords of long-dead warriors, they all rust away in the stillness of the plane, under a layer of iron flakes flurrying about like snow. The unchosen few who wander here are wholly alone, with no family, no gods, and no hope, surrounded by naught but silence and the constant ringing of the plane. The sound of Acheron, the infinite echoes of swords clanging against shields, of great steel cubes clashing together, swirled together into one long whine in your ears, now muted, but which will never fade.

No ringing of any bell is ever truly forgotten in Acheron. They only ought to be.

* ***Bloodlust.*** *While in* *Acheron,* *a creature gains temporary hit points equal to half its hit point maximum whenever it reduces a creature to 0 hit points.*

Anywhere within its borders, Acheron will reward you for prolonging any war, the promise of a physical reward encouraging further conflict where none was necessary. In Thuldanin, however, this bloodlust is empty; in a moment of passion perhaps a creature may die, and you may grow tougher from their death, but in Thuldanin who else will you turn to with your newfound constitution? You are alone with the ringing of the bell, and eventually you will rest for the night amongst the trashed tanks and the discarded chariots, and the gift will fade. Another death wasted.

Like in the rest of Acheron, the clanging and clashing of battles past rings out forever in an infinite echo. Each time two cubes cleave into each other, or a tall ruin falls, the *bang* never fades. In Thuldanin, this sound takes a low, bassy form, pumping in your heart with dread.

### Travel and Survival

A mortal traveling to Thuldanin will not survive for long.

There are many reasons to travel to Thuldanin. No one is keeping track of the remains of ancient wars, and many treasures and items find their way here from the material plane. It is said that on certain hills in certain fields, where now forgotten battles were once held, there appear burrows underground. On certain nights, when the moon is right, or late evening on cool, autumn days, they appear. Wandering souls who venture into the wrong path at the wrong time exit to Thuldanin.

If you are already in Avalas, and you are not already dead, it can be extremely difficult to get to Thuldanin. There are two main ways of traveling from Avalas, to Thuldanin: Lethe, and the Styx. Hiring a merreneloth to ferry you along the river Styx will require the least hassle, if you have the money to pay them.

Whether you find these natural passages, or whether you find some lord or merchant to front the money for a tuning fork and a spell scroll, it can be extremely lucrative to dive into Thuldanin and sack it for its treasures.

However one must move quickly. Everything rusts in Thuldanin, and the treasures you seek will not hold their value for more than a few days regardless. The vast majority of metal on the plane is reduced to a cake of rust adhered to a tunnel in an iron cube.

Monetary interests are not the only reason to hurry; if you stay on the plane for too long, more than a few hours, the portal will close behind you and you will be trapped. Then you'll start to rust too.

* ***Forgettance.*** *Any creature who spends a day in Thuldanin must make a Constitution saving throw with DC (11 + 1 for each consecutive day spent in Thuldanin). On a failure, the creature begins to rust and is restrained. A creature restrained in this way must continue to make the saving throw for each day spent in Thuldanin, and becomes petrified after an additional failure. A creature restrained or petrified in this way can be cured with a lesser restoration or a greater restoration spell respectively, or with similar magic.*

Like Avalas, Thuldanin is broken up into giant steel cubes that hover in the infinite expanse of the plane. The cubes here are smaller, few being any larger than a single city on a face, and most being no larger than a particularly tall building. As a result, flight is more necessary to traverse this layer than the layer above.

Th' knuckles naught but bones
These hands are worn by korred's ire,
scraping merchants' coal
I'm not afraid o' death no more
Not th' first one, layin' low.
I fear that this scraping has all been for nothing
and no one will ever know.

Despite the dead nature of the plane, there are a handful of inhabitants which call it their home. Creatures that hide from the fires of war, collecting their trinkets and trash from a place no one will ever find them.

## Hammergrim

the old ones turned your fathers into shitty dwarven stirge.
But, the magic deep inside you may prevent a fate far worse:
to be singing hymns instead of this old shitty dwarven dirge.

The cynical duergar live their lives in bitter hatred of the lot they were given, misdirecting their ire towards the fortunate surface races instead of their dark oppressors: the unknowable Illithids, and the unconquerable drow. Their god Laduguer preys on this belief, reinforcing that life is worth nothing and nothing will ever get better. Most duergar souls remain unclaimed by Laduguer, and sink into the depths of Acheron, but key clerics and fighters are chosen to live in Hammergrim, Laduguer's realm in Thuldanin.

**Arcane Mutants.** The duergar were experimented on by Illithids, and have magic power in their veins. It is common for wizards to set up towers in or around Hammergrim, as well as other powerful creatures such as rakshasa, eladrin, and modrons. These visitors capture duergar and experiment on them further, detecting what effects such experimentation has on a humanoid. These duergar usually bitterly hate these arcanists coming to abuse and inspect them, but will rarely take meaningful action against them, electing instead to wallow in their hate and self-pity until they are released or killed, where they will be resurrected anyway if Laduguer wants them. They, like all other souls existing in Thuldanin, are forgotten, cynical, and forlorn.

**Temnokar, the Pit.** Laduguer himself resides with his daughter Duerra in Temnokar, a coal mine eternally shrouded in magical darkness. For each hour spent within the pit, a living creature must make a DC 17 Wisdom saving throw, becoming overwrought with despair on a failure. The first time a creature fails, roll on the long-term madness table in the DMG. The second time, they gain the following flaw: "Nothing I do will ever matter, so there is no reason to do anything at all."

### **Hammergrim Encounters:**

* **Urdlen.** The gnomish god of greed and murder lives in Hammergrim, picking off duergar to gain the resilience from Acheron's Bloodlust when it begins to grow weak. Some say it would be dead if the temporary hit points from bloodlust ever wore off, but it would have to be an extraordinarily weak deity for these rumors to be true. As is, adventurers should be on guard against an enormous, pale, hairless, blind mole digging around the wasted, rusting cube.*Depending on the nature of the challenge you wish to present, and power you believe Urdlen might hold, you may use the statistics of a bullette, signifying that Urdlen is a weak, vain god which holds no power; a huge-sized purple worm with the bullette's burrowing trait; or Zaratan (VGM) with the purple worm's burrowing feature, signifying that Urdlen is still a god on the power level of any great being of the lower realms, despite having fallen far from the likes of Garl Glittergold.*

* Joiranta, an **elven mage** who erected a wizard's tower in Hammergrim. They are currently dragging two chains, attached to two duergar she intends to kill and autopsy. They will be confused if the players insinuate they are doing anything wrong by vivisecting intelligent creatures, and the duergar will treat the ordeal as a frustrating inconvenience if woken up.
* The **sorrowsworn** (MTF), though native to the Shadowfell, have found their way to Hammergrim, attracted to the despair and bitterness of the duergar. Because of these occasional portal to the Shadowfell, the sorrowsworm can sometimes be found elsewhere in Thuldanin, having wandered the desolate wastes out of Hammergrim.
* Bordul, a **duergar warlord** (MTF) who was killed by being bathed in the positive energy plane. He has resistance to radiant damage and can cast *cure wounds* at will, and is amassing an army of duergar warriors to rebel against the depression and despair of Hammergrim, to eventually claim their rightful place in the upper plains in the halls of Moradin.
* Jeria and Messul, two **duergar soulblades** (MTF) on a mission to hunt and kill Bordul, the Lord of Light. He is a traitor to all duergar by insinuating that Hammergrim can be escaped, insulting them by suggesting that there is anything that can be done to save them.
* Klothys, a **clay golem** with a conjuration wizard's "minor conjuration" class feature. They were created by the wizard Iogan, hoping to trap and study the duergar, and given the task of luring the duergar to the wizard's layer, but they do not understand how to entice a duergar. They can be found conjuring up flowers, sugar, music boxes, colorful candles, and silk or cotton blankets to offer the duergar, all of whom are thoroughly uninterested.
* Cailinna, a **dwarf priest** of Sharindlar, dwarven god of mercy and healing. She can open a portal to Sharindlar's domain to save them from a positive afterlife, but the duergar she approaches attack her. She may approach the party for help convincing them to save themselves.
* A **cadaver collector** has been collecting duergar that aren't dead, pinning them to the rusted metal edges on its back.

## Sargasso, sea of memories

he died the first death, so they say
-and though never was forgotten
none remember him today.
If you dive on certain nights
into the lake, when the moon is right,
his memories misbegotten
will the water bring to light.

In Acheron, the river Styx falls from floating cube down to the next in thundering torrents of dark water, like a waterfall. it splashes down on one cube, flows to the other end, and falls off once again. Because gravity has no consistent direction unless you are on a cube, the Styx flows falling erratically and violently, much like the plane it is on.

In Thuldanin, one cube the Styx intersects is Sargasso, on which the river pools into a great sea which covers most of the cube. The Styx is a river of memories, and steals the memories of the evil dead and anyone who plunges beneath its surface, and those memories flow down the river, starting at Pandemonium and accrueing more memories on their journey down to Acheron. In Thuldanin, the river pools, and memories accumulated from all across the lower planes stagnate in the waters, mixing with the refuse, rubble, trash, and waste from long forgotten wars that coats the plane.

### Sargasso Encounters:

* Exetus, a wealthy **mage** riding in a **merrenoloth's** skiff. The daemon is ferrying them out of Hell and back to their wizard's tower. Exetus is greedy, and if a wizard is traveling with the party he may bribe or demand that they stay with him for a night so he may copy down any unique spells in their spellbook. He may also try to buy any magical items the party carries, and take it as a personal insult if they refuse.
* Kzzlbrant, an **arcanoloth**. She is searching for lost secrets of interest using a long cylindrical tool she paddlels in the Styx with like an oar, which telepathically whispers arbitrary memories to her. So far, she has heard secrets of interest only to the soap operas.
* A **reduced-threat glabrezu** demon which fell into the river styx and was swept away here. It now has an intelligence score of 1 and can speak no languages, but will still attempt to destroy anything that comes close. *A reduced-threat monster has half its maximum hit points and a -2 penalty to attack rolls and saving throws, and awards half experience points.*
* A **merrenoloth** ferryman approaches the players and offers to give them a ride to any of the lower planes. It will cost them 1000 gp for each plane they travel through, and 500 gp for each layer within a single plane they travel through. The merrenoloth demands a single gold piece up front, and the rest of the pay meant at the end of the voyage (but before docking against land). If the party attempts to stiff the merrenoloth, or the merrenoloth suspects they will do so, it capsizes its ferry and dunks them into the river Styx.
* Meldeor, a **darkling** (VGM) who has traveled here from Limbo. They are searching for the secrets of the curse that effects all darklings, so that they can unravel that curse and return to the light. They will not find it, but they will find the memories of a now-dead kraken priest, whose master is intending to attack and subjugate the darklings in Limbo.
* The soul of a dead **duergar** who no longer has a name. They wandered from Hammergrim long ago, and found themselves here by the Styx. After spending many centuries here by the Styx, they have an intelligence score of 5, and they seem much more at peace than the other duergar on the plane. *They can still speak the languages they knew in life.*
* An abandoned iron tugboat that can sail the river Styx. It's been thoroughly rusted, but a character proficient in smith's tools or vehicles (water) along with a character who is proficient in arcana can spend a long rest studying and analyzing the boat together, learning how to construct such a vessel. The two characters now have the knowledge to construct a new boat, equivalent to a **longship** (GoS) with a hull AC 18 and the ability to sail the river Styx if the boat is transported there. Doing so requires at least one character with proficiency in smith's tools, 1000 total hours of labor (which can be done simultaneously by multiple characters each proficient in smith's tools or arcana), 15000 gp, and a brain gem from a slaad. They may never know who originally constructed the ship, nor for what purpose, nor why is has been ultimately abandoned.
* An **Archon,** a good celestial being of Law. They have come to the lower planes to bury a book of evil secrets, dissolve it in the Styx, and allow the memories to stagnate, hidden and unclaimed in Sargasso. Eventually, they will flow down the river and be trapped in Ocanthus. The players can dive into the Styx after the Archon sinks the book, receiving the dark knowledge if they succeed on a DC 19 Intelligence saving throw and falling under the effects of a *feeblemind* spell on a failure, but the Archon will question them about their intention to do so, and cosmically knows if they are lying. *For the Archon, use the statistics of an* ***Archon of the Triumvirate*** *(GGR), or of a* ***planetar*** *angel.*

## Lethe, Spring of Oblivion

and whose immortal deeds doth shake the very soul,
seize up the nerves,
and melt the will;
and by whose power I have seized Malbolge,
forced it ope,
and set infernal horrors free
and brought forth awesome fyre in disgorging hell.
Let it be known to ye, red masters, when this contract be fulfilled
-which even now the ills of age beset me-
I'll bring thy secrets with me to the grave,
the secrets of thy summ'ning be forever kept from reach,
and flee to th'ends of time and hell.
Thy book of secrets will be drown'd deeper even than the monstrous mollusks live,
and my soul retired t'oblivion.

There is a natural portal between the layers of Acheron, though it is dangerous to travel. Lethe is a steel cube about the size of a city, and on two opposite faces there are mirrored rough, steel mountains protruding from its surface. Both of these structures are filled with the water of the river Styx, which destroys your intelligence and makes you forget, and at their peaks is an opening to this deluge. The mountains are each topped with a swirling whirlpool of black water. Once every d4 hours, both sides erupt, dousing all of Lethe in a shower of this mentally damaging water; a creature caught in this rain must make a DC 16 Wisdom saving throw or be put under the effects of the feeblemind spell, and forget 1d6 days of their life for each day they stay under these effects. The ground here is always wet, and this can be dangerous to a character who is knocked prone without proper protection, who may take 2d6 psychic damage if they fail a DC 16 Wisdom saving throw. Because of this awful moisture, there are lichens and plants that grow all over Lethe, especially near the two peaks, that induce a trance-like state of obliviousness and have powerful amnesia-like effects.

Legends say that Lethe was build by a powerful archmage, who wanted to create a hub with which to travel through the planes. If you plunge through the whirpools of black water in Lethe's twin peaks, you will be expelled from the river Styx in either Avalas (the first plane of Acheron) or Tintibulus (the third plane of Acheron). It is impossible to tell which peak leads to which plane unless prior knowledge is given from a creature who knows. For most creatures, this travel will render them simple and empty, but there are ways to protect yourself for the passage, and there are certain creatures immune to these effects.

### Lethe Encounters:

Two mezzoloths scraping up the lichens of Lethe, and selling a drug called Algernon, made out of both plants grown from the waters of the Styx and similar plants grown from the waters of the Oceanus. They are selling a weak dose for 10 gp, and a strong doze for 50 gp. When a creature consumes the drug, their intelligence score either increases by five up to a maximum of 22 for 1d10 hours, after which they lose this increase and their intelligence returns to normal, then decreases further by 5 to a minimum of 3 for an additional 1d10 hours, after which they return to normal. If the dose is strong, they also add their proficiency bonus to any intelligence checks made during the first period, and subtract their proficiency bonus from any intelligence checks made during the second period.

An adult red dragon bursts through one of the two peaks, bathing half of Lethe in dark water as though the peak had erupted. The dragon's intelligence has been reduced to 1, and will blindly slaughter anything that comes into sight without succeeding on a DC 21 Wisdom (animal handling) check.

An abandoned wizard's hut, made of moist, slimy, run-down wood and about to collapse on itself. It contains 500 sp, 200 gp, an archmage's spellbook, an amulet of the planes, and a periapt of wound closure, all of which have been rusted and turned to stone by the plane. They can be restored by a wish spell or by being dipped in the waters of the river Oceanus. There is also a scroll of black water breathing, a 4th level transmutation ritual spell with a casting time of one minute, a range of self, a duration of 8 hours, and something from a lower plane of existence as a material component. It is identical to the water breathing spell, except that it also makes the chosen creatures immune to the effects of the river Styx.

An oblex (MTF) that has settled down near one of the peaks. It has learned to steal memories from the water of the river Styx, and will attempt to lure intelligent creatures to be shoved into the water so that it's memories will be added to the source, and extractable by the oblex.

A black pudding that has formed out of the slimes in Lethe, which have grown saturated with the waters of the Styx. Whenever it deals acid damage to a creature, that creature must succeed on a DC 19 saving throw against the synaptic shock spell, and it can cast feeblemind once per day.

A tridrone in control of three duodrones, which in turn control a total of six monodrones, all of which are digging away at Lethe with picks and shovels. They want to destroy Lethe, because the portal between the layers of the planes cheapens the ability to travel between them, but if left to their own devices they will open up a hole to the black-water-filled inside of Lethe, and douse themselves in the water.

Elshkae, a dryad who has lived for an extended period of time in the mists of Lethe. They can no longer speak any languages, and they cannot form new long-term memories. Their intelligence is 8. They are always under the effects of a mind blank spell, and allied creatures within 5 feet of them are affected as though they were wearing a ring of mind shielding.

A spykeeper's feldar, a pale, polished stone, worn smooth by tumbling down Lethe. It radiates a blacklight, emitting dim light out to a 5 foot radius, and any writing or books that are bathed in this light for 1d3 minutes disappears, leaving only blank pages.

## Elephant's Graveyard

This place is the tomb of King Elephant.

Elephant ruled over the dragonborn in ancient Abu-Ibramaya. He was said to be the son of Tiamat and Sormaust, the first black abishai, making him a black half-dragon cambion demigod. His empire brutally dominated everything west of the mountains for centuries, and when he eventually passed away, his tomb was built the size of a city unto itself, and thousands of workers were trapped inside, underground, living in the great tomb-city.

Eventually, however, even that immense feat passed away. The calcified remains of ten thousand dragonborn line the ruin, rusted halls. It drifts forever through the space of Thuldanin.

### Elephant's Graveyard Encounters

The negative energy that permeates the plane occasionally gives rise to the preserved, stony remains of the dragonborn buried in this holy place. They will fight to the last to deter intruders in the tomb. Use the statistics of a half-dragon mummy, with the following changes: the tomb guardian is not vulnerable to fire; the tomb guardian has a quasit's "Devil Sight" trait; the tomb guardian only speaks draconic and infernal. You could use the statistics of a half-dragon Mummy Lord instead.

A group of 4d6 black kobolds, who are hostile towards the players but will not deliver the first blow. They have devil's sight and immunity to fire and poison. They claim to be the first kobolds, the direct descendants of the ten thousand dragonborn entombed here, who eventually adapted to the fiendish dark.

Ashtael, a blue abishai (MTF). They have come to study the temple, and re-discover any lost secrets the ancient abishai of this long dead empire may have held.

Three dragonborn archaeologists with an explorer's pack and two dungeoneer's packs. They were exploring an ancient tomb near Third City, and they don't know where they are or how they got here. They have only one ration left each. Use the statistics of a guard\*, but a dragonborn.\*

Two nothics, part of the remains of King Elephant's divine court wizards. They have the power to curse a creature with future undeath; the next time that character dies, they awake one round later as an undead. They retain all of their class features, they gain immunity to poison and necrotic, their skin appears dead and pale, and every 7 days they must succeed on a DC 15 Intelligence saving throw or their Intelligence score decreases by one.

A giant owl guarding an ancient buried library deep within the tomb. They will only allow creatures to enter the library if they first contribute some piece of knowledge to it.

A cadaver collector has been trapped behind a sliding-door trap. It is desperate to escape.

A steel predator is stalking the halls, having been lost of hundreds of years. It was sent to assassinate Jel'Kyrath, a gold half-dragon devil worshipper who retreated to the Elephant's Graveyard after decimating the City of Sigil with their army of fiends. It is unknown whether or not Jel'Kyrath still lurks in these halls.

### Legends of the Plane:

It is said that the archdevil Moloch (MTF), exiled prince of Malbolge, lord of child sacrifice, called bitter and betrayed, can be found wandering the wastes of Thuldanin. He searches for some ancient secret, a powerful artifact or the key to a mythical spell, which might grant him the power to reclaim his dread warden's-throne.

Sahuagin legends tell of Welshrine, the Shark of Ages Past. This flying giant shark roams the wastes of Thuldanin, and the evil god Sekolah can see through its eyes, in this way she knows the secrets of wars from long ago. If Welshrine finds anything of sufficient value, it devours it in its horrible jaws, so that no enemy of Sekolah might ever use it against her.

The Wraith of Lore is rumored to wander these ancient battlefields. They are an allip (MTF) who formed on the plane out of an adventurer years ago, upon discovering the eldritch remnants of some aberrant war. They have lost their mind, but over the many lifetimes in Thuldanin they are said to have learned every secret fact of any lower plane, and the complete histories of all battle in either the lower planes or the material plane. They cannot speak beyond vague whispers, but if you come to them and open your heart, and give them some piece of yourself, the Wraith of Lore will grant you whatever piece of knowledge that you seek- at least, that's what the storytellers have come to understand.

Mad wizards and insane oracles speak riddles of Ashtokllyenth, the dark star of rust. In their manuscript "Star Spawn of Hell," Maglubiyen professor Ni Xiao hypothesizes that Ashtokllyenth resides in Thuldanin, where they travel from iron cube to iron cube, corrupting and consuming what secrets remain here. Adventurers report encountering star spawn who praise its name upon traveling too far into Thuldanin.

## Rust Dragons

Their hands grip their war staff. Holding strong.
The dragon's hide is segmented and brittle, a dull dark orange. It boasts the wings of an enormous butterfly; two antennae sprout from above its eye-ridges; its fat, yellow tail hangs beneath it. As the dragon opens its mouth, the war-mage raises their staff and begins to incant; fire sprouts from their staff, expands, and solidifies into a magical barrier of red, through which no fire can pass.
However, no fire comes; out of the dragon's mouth comes a spray of clear liquid. The war mage instantly recognized the smell of the gas bombs the hobgoblins used, and only barely covered his face in time. The liquid passed easily through the magical barrier, and began to bubble on their armor. The armor's color began to turn.
The dragon flew up again, then began to dive downward onto the war mage. In the corroded armor, they could not move. They grasped their staff, whispered a hurried cant, and disappeared in a flash of smoke, leaving their armor behind. The dragon devoured the rusted armor in a single gulp, and left the embarrassed wizard naked and alone.

Rust monsters are some of the most renowned and feared monsters to dwell in the dungeons of the world. Unprepared adventurers are left unarmed and undefended in the wake of the creatures' corrosive touch, regardless of whether they slay the beast.

Little known fact, rust monsters are the adolescents of their species.

When a rust monster has eaten their fill, and grown to a sufficient size, they somewhere find their way back to their home plane: the endless battlefields of Acheron. Here, they cover themselves in great cocoons and emerge as dragon-kin, and wreak terror on the inhabitants of the plane. The majority of rust dragons live in Thuldanin, though they can be found in Avalas and Tintibulus. They eat the metal that they rust, including feasting on the iron cubes themselves. Scholars speculate that one day, these creatures will devour the entire plane of Acheron.

* Use the statistics of an adult copper dragon with the following changes:
* The rust dragon is lawful evil, and can speak either infernal or modron.
* The rust dragon loses the "Slowing Breath" breath weapon option.
* The dragon gains a rust monster's "Rust Metal" trait.
* The dragon's "Bite" and "Tail" and "Acid Breath" actions gain the effects of the rust monster's "Antennae" action.

Optional Rule: Potency. Remove each instance of the word "nonmagical" from the rust dragon's stat block.