Aberian Arvanxi, of course, fled the country by Teleport in the first moments of the war. He managed to evacuate most of his treasury, too. He is living out the end of his days in luxury in Absalom, in a fruitful partnership with a wizard powerful enough to keep anyone out except the archmages, who are Good and thus above seeking revenge.

So, to be entirely clear, the great manor Vaneo Arvanxi now belongs to the current Lord Mayor of Westcrown, Pau-Roger Santcliment, a friend of the Archduke Shawil's through their mutual investments in Osirion's naval shipyards. He was appointed to this job because he's good at large construction projects. He's in the process of converting three wings of the palace into diplomatic embassies and houses. It's going slowly because they were full of horrible creative exercises in making your palace deadly to its own staff. 

So we're burning that place to the ground and killing everyone inside, right?

Absolutely!

He's got a crystal ball, for contacting his shipping partners in other cities. He rushes anxiously down to the room where he keeps it. There's no point in trying to contact an important person with a crystal ball, but he can try their assistants and associates, where he's met those, can keep trying until he gets a scry good enough to message through it. The Bachuanese fellow who lives with the Archmagi Cotonnet. The frog who lives in their backyard. 

"Excuse me? Excuse me? There's riots in Westcrown. Could you tell the Archmagi to come and make it rain again? Thank you for your trouble."

The frog who lives in their backyard looks startled, but emerges with froggish lack of grace from the pond and heads into the house and vanishes because the house is unscryable.

"Where've the archmages got to? I've got a fellow says they're needed in, uh, some place. Sorry, I should've written it down -"

      "They're needed in some place."

"That's what the fellow said. There's riots in - Westham?"

       There's a wand of Sending in the house, one of the good ones that can cast immediately. It's fetched. 

He should have seen this coming. He should have stopped it. He can think about that later. 

Riots in Westcrown, he tells Naima over the telepathic bond, just in case she hasn't heard. And because nobody's told him anything more specific, he teleports a thousand feet in the air above the center of the city. Where does he see flames? 

In the Rego Sacero, and in the Rego Aerum, and the Rego Pena, and the Rego Laina and -

...OK there's a lot of flames, everywhere. Crowds with torches, mostly. Some individual - for now - burning buildings in the richer parts of the city. The start of a larger inferno just east of Tarrasque Boulevard.

Fine. He'll start where the flames are highest. 

A Trumpet Archon is no taller than a tall man, measured head to toe, but it's the twenty-foot wingspan that gets peoples' attention. That, and the marble skin with golden veins, or possibly the eyes – like pools of liquid sunlight. To behold one is to feel an overwhelming sense of peace and calm, a solid bright assurance that the world is just. The sound of their trumpet paralyzes everyone who hears it within 100 feet, a fact which is more relevant for crowd control. They can heal, quite a lot. They'll need that too. 

He summons four of them. One by one, they sweep out over the city on vast white wings. They can teleport – will teleport – but for now, he wants them to be seen. 

With that done, he'll fly up into the sky and start to bring the rain. 

"Did you get the archmage? They're burning the place down!" he demands of the frog-man. 

        "Yes, yes, I told someone who knew how to contact him, he's on the way, calm down."

Back at Vaneo Arvanxi, the mob has breached the outer perimeter and are burning the botanical gardens full of exotic plants imported from distant continents. It's not that they have anything against botanical gardens, per se, just that these plants are probably evil plants, and are at any rate both flammable and on the way to the palace.

Control Weather has a casting time of ten minutes. 

The archons sweep through the streets, leaving the mobs paralyzed or placated in their wake. There are only four of them, and the Vaneo Arvanxi is a ways outside the city.  

There are guards, of course, who've fallen back to the palace in a fighting retreat. They do not hold the mob for very long.

They breach the palace, leaving dead rioters and dead soldiers scattered in their wake, and find the twice-damned diabolist mayor, and string him up.

Oh for fuck's sake. Mass Pain Strike. Is the mayor dead already.

Not quite! "I'm innocent - take me to Almas -"

"I'm not a ferry service." She'll dump him at the temple of Abadar, instead. 

Naima taps him and closes his injuries. He can sit inside with the others. She has more people to tap.

An archon glides over the crowd at the Vaneo Arvanxi and raises its trumpet. Everyone who hears it feels their legs turn to lead, frozen in place with awe. The others run. The mob scatters like a mudslide, pulling the weak and slow and paralytic down and crushing them beneath its collective weight. The archon lands, casts mass cure light wounds, and winks out of existence on the material plane. 

Above them, the rain starts falling. 

It takes another ten minutes for the rains and winds to really pick up. The crowds retreat and disperse and stumble home or into whatever warm dry places are nearby. The flames go out, one by one. The city stills, and the rains wash the blood away into the sea.