Osirion did not actually want this at all!

Some of them, at least, were expecting that it would happen eventually.

What kinds of spells affect transparent tortured soldiers. Can you turn them? Heal them? Frighten them? Plane shift them? Paralyze them with waves of ecstasy (look, some people didn't prepare their spells this morning with an invasion from Hell in mind).

Turn them: No, they're not that kind of undead. Heal them: Oooh, yes, thank you kindly, they appreciate the boost! Frighten them: No. Plane shift them: Sure! And then five seconds later the very same soldiers are back. Mephistopheles laughs at that last one, a great loud booming laugh that echoes to the nearest city. Well, that's delightful, but no, his soldiers are just not in that kind of mood, but he's sure they're flattered.

Would they like to try anything else? This Archdevil is having so much fun.

Teleport, Polymorph, obviously lots of smiting evil and so on, Imprisonment, Mage's Disjunction, Mass Suffocation, someone can Wish that they were gone entirely and if that doesn't work someone can Wish they were in the middle of the ocean and if that doesn't work someone can WIsh they were invading Heaven even though perhaps it could be argued that's a fucked-up thing to wish or something...

Teleport: Yes, and then no, rather like the plane shift. Polymorph: Yes, and then the fire rain lands on the polymorphed creatures, and then no. Smiting evil: Yes, and then no, when the soldiers 'die' and then come back. Imprisonment: No, they decline to stay imprisoned. Mage's Disjunction doesn't even tickle. Mass Suffocation doesn't appear to do anything at all. First Wish doesn't work, second Wish briefly works and then doesn't. Third wish does nothing at all, Heaven has defenses against that sort of thing, and my that's entertainingly counterproductive, what would they have done if he'd conquered Heaven, hm? They'd be much, much worse off. Not that he'll tell them.

Someone would probably scold that mage if they didn't need all the help they could get. 

(Wishing they were invading some country on this plane that isn't Osirion is considered but it is decided this is really a pretty evil thing to do and this is the sort of moment where one should keep an eye on where they want to end up.)

So the fire rain seems like part of the problem here? Is it responsive to, like, freezing spells or weather-altering spells or being teleported off or shifted into other planes or any of that?

Freezing spells: Some, but not enough to really matter. Weather-altering spells: No, it's a bit too hot to be put out that easily, though there certainly is some ominous smoke going on now. Being teleported works for the specific fiery droplets, but not enough to matter. Same for shifting to other planes. The source of the fire rain seems disinclined to go away, no matter how much fire rain they happen to directly put out or avoid.

It's potentially an opening, though, which is something.

Honestly they ...need Abadar to show up. But maybe he's busy and they should try to mitigate the damage in the meantime.

If they simultaneously put out a lot of fire rain and smite a lot of evil those ones stay dead until the rain resumes?

Nope! They come back right on time, hearty and tortured as ever.

If they put out a lot of fire rain and do a lot of polymorphs?

That has some effect, actually! But they have to keep putting out the fire rain, and keep all of the polymorphed soldiers in one spot, and—

—then Mephistopheles himself shows up and sets everything very much on fire, and the soldiers are back and oh wow that's a lot of death right there oh right it's not just the army they're dealing with, is it.

Well, they know (one thing) they need to do. The problem is just that they...cannot do it. They don't have that many high-level casters and other countries' adventurers are mostly sensibly staying out of this one and people who aren't sure of their alignment should maybe...board boats? 

That does seem wise, yes.

Mephistopheles lovingly rains some fire on the boats, just because. And really, if you don't take the time to enjoy your job, what's the point of being evil?

Nine hours into the invasion, and the pharoah of Osirion gets a sending from an unfamiliar person: Epic help incoming. Push enemies to tiefling. Stall and prepare until we make our move. Wall leftovers underground with stone once we’re done. Conserve forces.

Well that's better than anything else he's heard today. It is of course completely possible that it's from Mephistopheles, but it is possible that it is not. Which would be -

- are there any tieflings to push his enemies towards, if he sees a way to do that?

No, just a lot of invincible soldiers made from the tortured souls of the damned, no tiefling obviously making himself appar—

He appears out of the sky in the form of a giant, crashes onto the most concentrated part of the battlefield, pounds his fists into the ground to deepen the crater, and then his polymorph drops and it becomes very clear that the form of a giant was actually much less scary than his actual form.

Yes, this tiefling is worthy of an article before his pedigree. He is definitely epic level. The invincible soldiers are still quite invincible, but he's fast and deadly enough that it doesn't matter, they get dusted as soon as they're done reforming, and then he's on to the next, and the next, and the next, and back around again, and all of these annoyingly invincible soldiers can just stay right here with him in this crater, invincible or no.

This is still as likely as not to be a trap but - they don't have anything else to try - 

They can attempt, with a lot of stone walls mostly, to herd enemies that direction.

Mephistopheles lands in front of the whirling tiefling, wings flared, and begins trying to personally kill him.

It does not take.

Snarling like an animal, eyes glowing red with demonic rage, the tiefling fights like a man possessed, with no care for safety or tactics, just kill the thing with as much prejudice as possible.

Then, just before it seems like he might fall despite all his impossible strength and maddened rage, the tiefling breaks something in his hand, murmurs a word, and disappears.

From the sky, arcane words are spoken, and a gesture is made.

Below the wizard, all of the army in a forty-foot hemisphere gets turned to frogs.

Mephistopheles resists the epic spell, somehow, glaring up at the invisible enemy in the sky.

"You again! Can't you just take a hint and stay on your plane?"

"No," says a patch of air, "not really."

And then she conjures a great celestial triceratops, which starts trying to skewer him.

"Done!" yells a chorus of illusionary voices.

Wall everybody underground with stone, they said. 

They can do that. 

Good.

Several minutes later, the tiefling, looking rather a bit more bloody and haggard, turns visible just as he is deposited gently on the ground by the pharaoh's forces.

"Never," he mutters to the air, "would I have expected to miss the kobold."

The air snorts, despite herself, then gets back to business. "Cleric!"

"And the nearest leader of the defense forces, pharaoh himself if possible," grumbles the tiefling, "we need to start coordinating to make any headway."

The pharaoh's not on the battlefield, this would honestly mostly be a distraction for his security and he can use his spell slots just as comfortably far away, raising the dead. The head of his guard is, along with the head of the military and the head of the church. They can talk right now, definitely.

That will do fine. Then this person would like to know the general state of the defense forces, what resources could be brought to bear, if there's been any new aid from other countries or planes in the past three hours, and yes it's fine to submit to a detect evil and a zone of truth or whatever they'd like before telling him any of this, he understands security concerns, it's just they're kind of in a rush right now, considering.

The wizard's greater invisibility ends while everything is being sorted out and healing spells are being applied. It's a bit hard to tell what she looks like, underneath the stoneskin and array of dizzying wizardly defenses, but she's... probably an elf? Either way, she looks rather antsy, looking over her shoulder and shifting her weight from one foot to the other.

"Could we be appointed a liason to connect with telepathically, to coordinate with?" requests the elven wizard of some sort. "It seems a poor idea to cluster together talking, however grave the circumstances and however necessary the debriefing."

Head of the military, probably. Then they can scatter to separate ends of the battlefield.

 Osirion has twelve people with ninth-level spells, all but one of them out for the day right now, currently resting. It has about a hundred people with the ability to come near this mess and not immediately die. It has an army that ...mostly...can't do anything, unless they have some bright ideas on what weapons to get them or anything. They're back in communication with neighboring countries now that the thing looks better than 'totally hopeless', and anyone who wants to teleport in is being directed to a concealed site about ten miles from here.

"We have scarce few allies to bring to bear ourselves, I'm afraid. Most of our forces are exhausted; we have a cleric comparable to your pharaoh, a handful of lesser spellcasters, a spell-resistant golem, a minor celestial, and two epic adventurers that are in Cania trying to stop this at the source. We're here to help you buy time."

"I'm going to cast a telepathic bond; I can connect six people besides myself. Two of those are going to be Valen and our cleric. Is there anyone else you would like connected on a telepathic network?"

The pharaoh, definitely.

"I'll need him and everyone else to be connected within seventy-five feet of me at the time of casting, so it's best if we go to him."

Valen looks like he's biting into a lemon admitting this, but: "And it's likely the Seer—our cleric—will be safer behind the pharaoh's defenses than ours, after the past week."

The pharaoh's guard also doesn't look delighted about this but - "that can be arranged. Does the pharaoh need to be on this plane for the telepathic bond to continue to function?"

"Yes." It's hard to tell underneath the very paranoid wizard defenses, but it looks like she's grimacing sympathetically. Probably. "I apologize, I know it's a lot to ask."

"Let me make arrangements."

She nods. "We, as well. Excuse me."

The wizard steps away, and casts whispering wind to send an update on their plans to the Seer and her rather meager set of guards.

They are going to have to bring the pharaoh back to this plane (aaah) and to somewhere where everyone can be near each other and then to somewhere defensible for him and the strange cleric.

They get to work on logistics for this.

Valen would pity them, if he didn't have a very similar problem, except with less resources, more exhaustion, and less harmonious allies. As it is, he is just highly sympathetic and cooperative.

Eventually, everyone necessary is gathered within seventy-five feet of each other.

The 'Seer' that both epic level adventurers look rather protective of is a charcoal skinned elf, with silver hair and a kind smile. She bows low to the Osirions, when the adventurers stop fussing over her and standing in front of her protectively-but-trying-to-get-over-it.

"My sympathies and support during dark times. I am at your service, Great One, and my abilities and allies at your command."

Valen looks even less happy about this. His mouth is possibly frowning hard enough that his face might split.

"Really. Again?"

"Peace, Valen, I will be safe in their care. We will not regret our trust, nor they, theirs."

The wizard rolls her eyes, and casts telepathy on the intended recipients instead of leaving the tiefling to pout about his trust issues some more.

He watches this with some fascination. 

Are all of these people in good health? Do any of them obviously need anything?

Everybody's physically uninjured; Valen's physically exhausted, but not devastatingly so. It looks like he's used to this kind of treatment. He is very unhappy about everything involved here.

Now that telepathy with the pharaoh is up, the Seer sends to the group:

First among the resources available that we could not carelessly mention aloud is a Mirror of All-Seeing. It is dangerous to use carelessly and requires a gentle touch, but with its use I can help spare your spellcasters from scrying needlessly.

What's going on in Hell? Your companions are there? Do they need anything?

The specifics are unknown to me— she sends an impression of her suppositions from a combination of her visions from Eilistraee, her brief glimpses of certainty through her mirror, and her general knowledge of the situation.

Mephistopheles has been planning this for a while, and unfortunately for the Seer, one of her greatest enemies was his favorite tool and puppet in this grab for power. The disappearance of a great hero coincided very conveniently with Mephistopheles's escape from Cania, and it's fairly obvious now that his meeting with Mephistopheles and subsequent departure to Hell was orchestrated by higher forces. Everything was just a bit too easy, just a bit too convenient, just a bit too fated. But neither is it, she thinks, entirely by the Archdevil's machinations. This was orchestrated by other gods, and not of the evil alignment. Veron Chandler was everything Eilistraee's visions promised him to be, and more besides, and it is following her goddess's (and others', she thinks) planned fate that he be in Hell right now. He has a long and painful path to walk, but he does not walk it alone. She believes with almost painful sincerity that everything he needs is already there with him, and that trying to aid him more might upset the fragile balance of fate that the gods have so carefully crafted.

—but I believe it is in hand, and that we should focus our attention on keeping as many of your people alive and safe as possible.

(Valen is politely holding in his powerful urge to scream. Somehow. Has he mentioned he is an atheist? He is an atheist, and blind faith is dumb.)

An....atheist.... in the sense of thinking that the gods are just very powerful people, or in the sense of - never mind -

Well, if they want to protect the people of Osirion they want to slow the march of the undead army across the desert, and the best way to do that is probably with weather, which in that part of the world is vicious at the best of times. So some people should be on that, and some people should come down with him to the catacombs that hold powerful people who died too soon, their bodies preserved with magic so Raise Dead can still reach them, and get them to the front as quickly as possible.

The Seer volunteers for assistance in resurrections, naturally. She thinks Nathyrra would be best suited for assisting with the weather, though she.... has the impression that.... she will need the assistance of a cleric of power and familiarity with Osirion, because of the nature of the rain of fire going on here. It seems Hellish - they need the opposite, epic wizard or no.

Valen has a somewhat scarily complete knowledge of devil tactics and how they wage war, and the best tactics to cause disarray and chaos among their forces, invincible or no. He'd like very much to confer with a general about these tactics, actually, if this place isn't too lawful to bring to bear the unpredictable tactics he learned from demons in the Blood Wars.

And while Nathyrra is fine with going to work on the weather problem, she is first and foremost an illusionist, so if there is anything they would like to hide from the enemy, that should probably come first before they ask her to go figure out how to make the weather have teeth.

There is not a law that military tactics have to be predictable though they shouldn't do war crimes. He sends a brief summary of what counts as that.

There's some very powerful clerics of Nethys she can meet if that'll help, and some of Sarenrae, and him.

How many villages in the path of this undead army are possible to hide as less intriguing-to-devils terrain?

Excellent, then they will get along well. Valen doesn't particularly like doing war crimes either, he will not be including that section of demonic tactics in his advice.

Nathyrra isn't picky on the deity of the cleric, but someone best with weather seems smartest.

A fair number, actually, especially if they get creative and do more than just hide the villages themselves. Hiding a whole village is difficult, but, say, adding a large twenty foot cliff that the Archdevil needs to go around to get to the village is not. If evacuation's viable for only some of the villages, then she'd recommend they evacuate those and make them look like an evacuation is ongoing while the Archdevil is passing by, to waste his time with a tempting target that turns out to be empty. They can similarly make other tempting targets in places that have nothing in particular, or disguise exits to underground safe bunkers in the villages themselves, or...

She has a lot of ideas and they'd probably be best suited with specifics, a map, an expert, and preferably some way to travel to far locations quickly without personally wasting spells.

Well he has those. A detailed paper map with careful illustrations of lots of places, good enough for a teleport, and some conscripted wizards with some teleports left and some fretting priests who moved to Sothis from various villages and who travel the countryside for services.

As it turns out, Nathyrra is very creative with ways to apply magic to disguise and distract from innocent villages. She has a certain level of practiced paranoia and familiarity with throwing off pursuers, and finds saving and protecting people in this way very fulfilling. Almost like she likes using her arcane powers for good, or something.

Somewhat regretfully, she doesn't have infinite illusion spells, and moves to working on a problem she's less familiar with and suited for; weather. She has a single Wish spell going spare that can be devoted to this, but it's important to really figure out what's causing the fire rain before she potentially wastes the wish getting the weather to do the wrong thing. Wizardry works best with understanding.

Valen is similarly helpful, though finds the whole affair a bit less fulfilling and a bit more with filled with bloody minded satisfaction at getting to harry an Archdevil. He can actually go fight the invincible army and Archdevil again, if they know of a way to get him out before he's killed.

The Seer is a cleric of respectable, if not quite epic, power, and is absolutely willing to use all of that power to the benefit of Osirion. Her first ninth level spell, courtesy of the domain of Good granted by her goddess, goes to summoning a great leonal guardian to slow Mephistopheles's army down.

The second is miracle. She has a few ideas for how this might be leveraged in their favor - maybe a miracle from her goddess could stop the fire rain, and it's likely Eilistraee would be willing to raise many, many fallen warriors that died before their time - but defers to the pharaoh's superior knowledge of what precisely his country and his people need.

He'd rather stop the fire rain, if she thinks she can do one of those. The dead could be raised tomorrow, and are mostly in (or on their way to) a good place anyway; dying fighting the forces of evil isn't very evil.

Valen could have a ring of Teleport?

She'll ask her goddess for a miracle to stop the rain of fire, then. For best results, she should wait another hour, until the moon is highest in the night sky. This is when Eilistraee is at her most powerful. Until then, she's happy to heal or resurrect or do other associated cleric things as the pharaoh would like; her prepared spells are at his disposal.

Valen would be delighted with a ring of Teleport, and will go cause mayhem with its safety net accordingly. He's going to need healing after this, but halting Mephistopheles's army for even a little while is worth the extra time for Osirion's citizens.

He waits until the perfect moment for mayhem, when it's most likely to aid their cause as much as possible, and then: mayhem. He enjoys it very much.

Mephistopheles... does not.

He rather dislikes feeling like a punching bag waiting for the do-gooders to get all of their hits in so they can all feel very special and accomplished. How about instead of doing that he, oh, hmm, he doesn't know....

Sneaks a small force of his undying soldiers past the front lines under invisibility, and to this lovely little port town to unexpectedly burn all of the boats and cause general mayhem? How about that? That sounds lovely. Then the inhabitants can be systematically flayed, and their fear, pain, despair and souls can be harvested to strengthen his war machine. Excellent, that's much better, now he has enough power from that to scorch the land ahead of his army, to see if it all burns properly or not. Oh! Look! That lovely little village exists right there in that illusioned terrain, he can tell by the smoke! They can get flayed too.

Mephistopheles must hate how few Osirians he has a chance at once they're dead. He and the Seer shouldn't waste spell slots on healing, for the most part, there are lots of low-level clerics who can do that though it's admittedly more annoying to be healed up by a sudden crowd of twenty bright-eyed young priests than by one who knows what they're doing. 

Instead they can raise the dead and send them off to - well, to those villages that haven't been evacuated successfully enough, or to the edges of Sothis, which he really doesn't want the enemy to even touch - there are enough low-level casters to mist the areas around Sothis in glitterdust -

Rather fortunately for Mephistopheles, there are no insurgents wandering into fields of glitterdust. Apparently he had no insurgent based plans for Sothis, or if he did, he certainly doesn't have them now. Mephistopheles is not dumb enough to send insurgents to Sothis through fields of glitterdust.

It's kind of hard to tell, from this distance, what with making war with armies in the way, but the Archdevil doesn't seem particularly perturbed by the constant resurrections of his victims. This is for a couple of reasons, none of which he is going to explain to the reader. Sorry reader, you'll just have to wait and see!

The Seer is perfectly happy to stick with whatever spells the pharaoh would like of her.

An hour passes, and her goddess's strength rises with the moon, and the Seer strides confidently to the highest point in Sothis with an open view of the night sky. Her prayer is simple and open ended; she trusts The Dark Maiden with her heart, her soul, and all the lives of those under her charge.

A miracle is not like a scrying, or a resurrection. There is very little ceremony in the magic itself. Divinely speaking, it's a petitioned request, and an opened door. Ceremony can be added, and some gods might find it polite or require it, to prove the sincerity of the request, but Lady Silverhair has no such requirements. This world is far from the one she's accustomed to, and the people it's for are not truly hers, but she is a goddess of good, and this Archdevil has done very much to hurt her wayward followers. It is not such an unreasonable request.

Falling fire turns from its angry red-orange to a shimmering silver to match the moon above. When it lands on flame, the inferno chokes and sizzles and starts to die, quenching them like rain. When it lands on evil beings, it sticks to them, outlining them for all to see in the smoke-filled night, regardless of invisibility. When it lands on all else, on the good or the neutral, it dissipates harmlessly, leaving only a faint chill against bare skin.

It's hauntingly beautiful, and shows no signs of stopping as Eilistraee's hour of power wanes. The silver rain will last until the first light of dawn.

Well then they'd better make the most of the time this gives them.

When the soldiers are not indestructible, Osirion's army can fight them. It wheels around and starts doing that. People who used all their spells can benefit from a shortened rest and then get out there and use them again. And they can drop a lot of rocks out of the sky, in places where the evil army is separated enough from theirs.

The soldiers are still unkillable, but they're no longer quite so unpolymorphable. While they come back from being killed, they still have to navigate around physical space, so dropping rocks on them slows them down twice over. Adventurers get up to various types of mayhem, lots of dead people are systematically resurrected, blah blah the good guys are winning blah blah let's get to the good part, Mephistopheles is getting bored.

So, it turns out that if you make a credible attempt to invade a country with the forces of evil, lots of citizens suddenly get very nervous about their afterlife situation. Such that if they're going to die and go to Hell anyway, and they don't have time to morally backtrack to make it to that silly Axis place that Osirion's so concerned with... well, it'd be smart to make sure that they'd end up on top upon entry to Hell. Mephistopheles is pretty well situated to make that happen, even if they don't get in to the section of Hell that he's personally in charge of. So if they could just be so kind as to sign their lovely names on this dotted line, he can get them set up in a cushy afterlife situation, guaranteed! Just summon some devils and help speed this whole conquest up, and everything will be taken care of soon enough.

Not to mention that whole thing about Mephistopheles's boss (Asmodeus, great guy to work with, really has a passion for his work, of course Mephistopheles wants to gain enough power to supplant him, but really that's just friendly competition) already having a foothold in this world, namely: Cheliax. It sure is convenient that Osirion's army is held up in a land battle with that army of his, it would be a shame if, say, some sort of naval force were to mysteriously show up on Sothis's doorstep. Like Cheliax's. Shortly after several baatezu are quietly summoned within Sothis's walls to sabotage its defenses. Did Mephistopheles say a shame? He meant delightful.