He doesn't carry diamonds around in his bag (although maybe he should), he can go hunt down one of Aroden's wizards and find out if they have some diamonds, or if there's any coal around here he can just make on right now, Restoration calls for a pretty small diamond right? 

He can what now. (Restoration requires only a very small diamond yeah).

He's the only Velgarth mage who can do it but it's not even that hard for him. Vanyel finds somewhere to make Leareth sort-of-comfortable and then darts around, asking people if they know who has either coal or a Restoration-grade diamond. He gets coal first, the army brought some as more portable fire fuel than wood, and so he can make a tiny diamond right there, cool it off with some wind, and hand it to the awed cleric. 

The cleric is so awed he can barely concentrate for a bit but he gets himself together and Restorations Leareth.

Leareth scrambles up from where Vanyel laid him against someone's pack, coughing a bit. "–Where... Oh. Thank you, Vanyel. Did it work?" 

It worked beautifully! Vanyel is gleeful about it!

Even after Restoration, Leareth doesn't exactly feel in top shape, he's probably very low on whatever kind of reserves Restoration doesn't address. It's nearly dawn, though, so he'll go back to his own tent and read a few more pages of the cleric spell list before the sun peeks up and he, alongside all the other clerics, prays for his spells. 

Abadar is there (well, a tiny cleaned-up bit of Abadar is there) to grant them.

Including third-circle ones, if he wants those.

Leareth absolutely wants third-circle spells! He'll take Channel Vigor, as many of it as Abadar is willing to give him. For second-level he'll take two of Lesser Restoration and one of Consecrate, and he'll prepare the innate reserves spell in all his first-level slots.

And then cast it right away first thing so his head will stop feeling so empty. 

Aroden Gates back to Egorian, his tour of the various towns complete, and checks in with Taver about any activity in the city overnight. 

Some civilians had medical emergencies and weren't sure if they'd get stabbed for going to a temple about them. There are some spies invisibly hanging out seeing what's going on and reporting deployments back to Cheliax. Otherwise the night was quiet.

Taver reports in that he's been keeping an eye out for people freaking out about things like that, and discreetly Mindspeaking them to alert them of the nearest triage area with volunteer clerics and Velgarth Healers, or warning a cleric directly to go offer help. The spies he can't do much about, although when he notices them, which presumably isn't always, he gives them the usual spiel about Aroden so they can report that back to Cheliax too and also so they know they're being watched. 

Taver has been one of the single most useful people in this entire war and Aroden is deeply grateful for his help, and understands that he must be very tired after twenty-four hours straight of war, but Aroden needs him for one more assignment. They're going to do another tour of Gating around between cities, dropping off whatever troops have been freed up after the active fighting in the other cities ended and have now had at least some rest, and Taver will broadcast a message telling them of the overall strategic situation and promising that if they surrender, they'll be occupied in an orderly fashion with no bloodshed. 

(Hopefully the mind control will help with this bit.) 

Egorian was the biggest city with the most resistance, and if he's stealing Taver he certainly isn't going to take any of their garrison too. Aroden hitches a Gate with Taver back to Ostenso. 

Taver skims all the accessible surface thoughts in town to get an additional angle on how the occupation is going there, while Aroden amasses some troops to move. 

Similar picture to in Egorian. The longer there's no response from Cheliax's armies the more people start to wonder if it might be true, but mostly they're still assuming it'll be false and the city will be retaken with a lot of bloodshed and they'll be in trouble for having cooperated. 

Also there's an underground resistance working on tunnelling over to where the invaders are camped so they can suck them into an underground sinkhole.

That is so delightfully resourceful of them! And also, nope definitely not. Aroden assigns some of Leareth's mages to watch the tunnellers and hold the ground together with a force-net so their sinkhole ambitions come to nothing; in the meantime he might as well let them tunnel without interference, it'll keep them from hatching some other plan.

He lines up a thousand soldiers, about ten of Leareth's mages, and a couple of the Heralds to go be visibly paladin-like and provide mindreading and telepathy coverage once he and Taver move on. They Gate out to the biggest city on his list of next targets. 

Taver, from the edge of the small city, delivers a telepathic message to everyone within it, in ringing steely tones. Aroden is here to reclaim Cheliax; within a day, he has conquered Egorian and another three major cities, taken the bulk of the Chelish army prisoner in another plane, and opened talks between their diplomats on terms of surrender. There are soldiers and wizards here to take this city; if they want to just surrender, they can be occupied in an orderly fashion without risking injuries or deaths. 

On the one hand the city leadership is clearly mind-controlled to be saying in the bland tones of someone who doesn't have a choice about it that they surrender.

On the...other hand maybe that means no else will be executed for complying? Given that they tried Break Enchantment and it didn't even work and there's no one here who can do more than that?

What do you do if you are going to die today if you refuse to surrender and going to die tomorrow if you agreed to surrender today? And going to Hell either way, though Asmodeus is a sensible person and finds more use in people who served him well, while those who betrayed him are only refuse...

No one actually stops the mind-controlled countess from announcing that the city surrenders.

Ten Velgarth mages and a handful of mid-level Golarion wizards spread out to guard all exits and entrances to the city; the thousand soldiers split up to patrol the streets.

A couple of Heralds pace around, the Companions passively mindreading for any signs of self-organizing resistance while their Heralds look around for people who might need help.

Aroden accepts the countess' surrender face to face, and then Gates back to the Ostenso camp to collect more soldiers for the next minor city on his list, and to find out if any of the countries offering help occupying cities have more of that available, clerics in particular, they'll want to reconsecrate Asmodeus' temples promptly. If so they should send someone who can teleport to the town in order to share a memory of where they've got volunteers lined up, and someone can do a Velgarth Gate to move them there. 

And then they move onward. 

Elsewhere (not exactly anywhere) there is a conversation (not exactly a conversation) that if it were rendered in human words (it cannot be) would go as such:

Asmodeus could order the lords of Hell out onto the battlefields in Cheliax, and then it would all be over; Aroden cannot stand against that, and his forces less so. It is not done, but there are few among the gods who could stop Asmodeus, if he were to do it. 

What they could do is make it worthless. And he is shaped like that, now, has been since the dawn of the previous day. If you do that, I will make it worthless; I predict that down this path lies the destruction of the world. 

He thinks that this is stupid, and should be reconsidered, and he doesn't see why, and while humans squabble in Axis over human terms for a human treaty they could discuss it, maybe, and see if there's some middle ground.

They could discuss it. 

He sees - a world where the cities are not driven by the desire of people to live in cities but by the desire of Hell to herd them there, where the inventions are not done by eager inventors who seek to reap the benefits of their work for their own sake but by frightened obedient people hoping to make their punishment less terrible. He knows what Asmodeus tells the people of Cheliax - that Asmodeus will rule over all the realms, someday, that Axis is not an escape because Axis will not last...