(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.