He's satisfied it's worth the risk.

He already has active:
Contingency (6th) - Moved to any plane other than the Material or Estrella's Bag of Holding: Homeward Bound (4th).
Mind Blank (8th).
Greater Magic Aura (4th).
Soul Vault (4th), permenancied.

He's already wearing his headband, Black Robes of the Archmagi, Boots of Teleportation, and a dozen other items.

Finally when he's ready:
Greater Invisibility (4th).
Teleport (5th), off of the Boots.

Surprise round: Silence (2nd, cleric only), cast off of a scroll.
Then he'll kill the rest of the family mundanely, before cancelling his Silence spell.

Maybe if I pray to the fairy, I'll get to try this conversation again.

Nice try, but it's still pretty obvious You're only pretending to be insane.

Hi Norgorber, cool to meet You here.
What is this conversation and why is it happening in a group chat named "People who are watching Stristyko"?

Tet, You can get Norgorber to give You budget by pointing out that You'd otherwise tell Iomedae stuff and Norgorber wouldn't want that.

Can I?

Hey Norgorber, I'm totally otherwise going to tell Iomedae stuff.
You should give me budget not to.

Yeah, no thanks, I'm fine.
This is some weird Nethys gambit and I think I'll keep My budget, actually.

Oh no, I screwed it up by saying the wrong things.

They finish casting the Control Weather.
The first drops of rain begin to fall.

Dispel Magic (3rd).

And he beats it on his first try.

May whoever just did that be damned to Hell.

If they're unlikely to get the fire out tonight the displaced residents are on net an asset, needed to help with the reponse. She'll order instead that they be pressed into forming a bucket brigade from the lake shore.
For this many seperate fires, all at once, it's not going to be enough.

She could open a Gate to the Elemental Plane of Water, high enough in the air that it falls as extremely heavy rain but not for very long. It'd likely be too destructive though. She could use a miracle, but the enemy can just do this again.

She could try to use lower-level water magic and just way more of it. Aqueous Orb (3rd), Sleet Storm (3rd), and Ice Storm (4th) exist, and though few will have them prepared they've got scrolls. The enemy would have to get much closer to the action to dispel them, and they've seemed unwilling to do that so far.

All that matters is how many scrolls they're willing to use, but their anti-fire scrolls are a limited supply. This might just be meant as bait before some other, more useful attack.

She could summon a bunch of Drowned Devils, who have Control Water at will.

They can cover a 120 feet by 120 feet square in up to 24 feet deep water if they've got a nearby lake or river to pull it from. Egorian has both a lake and river. It'd take dozens standing in a row to push the water far enough inland through the sewers that enough volume can be expelled where the fires are.

If the Sarglagons focused on getting enough positive pressure up the sewers, with enough powerful mortal casters adding their own control water it could get the largest fires all out quickly.

Today is the only day that Egorian doesn't have enough powerful mortal casters to do that. They can at least flood the sewers most of the way, and give a closer location for the commoner bucket brigade to fetch water from.

An imp can lift a type II bag of holding and fly it around at 50 feet, 200 feet if the imp "runs". If they filled it with 500 pounds of water and dumped them on the fires and flew back in a cycle, it'd maybe be enough if they commandeer every such bag of holding in the city, and they'd only need a fraction of the imps because Egorian has really too many imps. The rest can help with the bucket brigade although they won't be as effective.

It won't put it out quickly but it'll get the fires under control and at least protect the rest of the city from it spreading. They can rebuild the slums later, better even, more centrally organised so that it's harder for the scum of society to sneak around in them.

She'll do more than one of them.

Mage's Decree: All available residents and devils must report to Sorrowgate to form a bucket brigade. Bags of Holding must be turned over for use transporting water.

And she'll authorize a fraction of their strategic scroll reserve be tapped.

She's the only person with enough Authority to do that, besides the queen and the mayor who'd be too dumb to think of it. It's obvious to her now why she's needed here personally.

Though she can't see her master and mustn't know his location, seeing the effects of his magic is always pretty. The great storm clouds of the highest wizards of the self-proclaimed strongest deity are dissipating ineffectually, as all attempts to defeat Stristyko are doomed to do.

She's still got more runes with which to attack either the crowds themselves or unattended buildings, which should she pick? She could also release her spawn again, though Stristyko said not to do that until later so she shouldn't do that until later.

You're probably wondering why Stristyko needs to put the runes on copper, rather than paper. This is because paper is flammable, which presents problems if, for example, he's imagining the runes being used offensively by a fire elemental.

A scroll of Summon Monster III costs 375 gp, and can summon 1d3 small fire elementals for a round per level. In that time they can pick up a stack of ten runes each, travel 50 feet a round, and read them at the front door of each house they come to, or at the feet of anyone who tries to stop them.

They like spreading fire, and are immune to it themselves.

You can kill a fire elemental, it's not that difficult really. You can either get close in melee and risk being caught in the blast the next time it reads a rune, or you can attack it at range. Still, it's a pretty good weapon.

Dominate Person isn't the only source of useful idiots.

Yeah, that. That's what she's supposed to be doing at this point.

Although in her case it's Summon Nature's Ally, and also it's cheaper to use the 2nd circle version and just do it more times, especially if it's off of scrolls.

She'll mix it up between that and regular dominates, and keep changing location in the hopes that they'll keep trying to find her.

Stristyko waits patiently another hour, as the defenders wrestle with the blazes made already and justify spending more resources against them.

He's worried they'll try another Control Weather, but they don't.

It's getting late, he's pretty sure they're not going to risk losing another 7th-circle scroll against a 3rd-circle counter.

There are larger explosions you can make with magic than just those, at proportionately higher costs.

Detonate (4th) has the ability to produce an explosion dealing 10d8 damage to all creatures and objects in a 15ft radius, and half that to a further 30ft radius, in your choice of acic, cold, electicity or fire damage.

The downside is that it's centered on the caster.

Burning Skeletons are immune to fire, and can be made with Animate Dead (4th).

Stristyko can control 30 of them without having to do anything clever or special. He can make far more than that, if he doesn't care about controlling them.

Suppose that, within the safety of his own lair, a lich periodically casts Possession (5th) on some of his own burning skeletons.

Suppose he then casts Contingency (6th), connected to a Detonate.

To do this, he would need to own a 1500 gp ivory statuette of his own burning skeletons, one for each skeleton he wanted to do it with.
Suppose the lich had at some point stolen the body of a successful master artisan, experienced with many materials including ivory carving.
Suppose the lich had raised the artisan as a Juju Zombie, because unlike most zombies juju zombies retain the skills they once had in life.
Suppose that, among the many other things this undead servitor is commanded to do, he makes incredibly artistic, genuinely beautiful ivory carvings of burning skeletons.

Possibly it is an Extended Contingency, and possibly it is a Maximised or Empowered Detonate.

Suppose he decides that the condition is the skeleton explodes when he decides that it explodes.

Even if you're not just outright stealing materials, you can sell a lot of the things a skilled undead craftsman makes at a profit, which you can use to buy more ivory.

It's really not that hard to break even, financially, when you're immortal and also a wizard. And the excess you can spend on the stuff that makes you happy.

The most important buildings in Egorian are made primarily of stone, but inside they're decorated with rugs and curtains and excessive finery to show how much better the occupants are than everyone else.

The Midnight Temple has a Lawful Evil forbiddance covering it's internal areas, and devotional spaces restricted to the faithful, and even higher security for the basement floors where valuables not so valuable to put in a demiplane are stored. The 60-ft cubes of the forbiddance don't extend very far above the ground, though.

The roof of the cathedral's main hall is supported by thick wooden beams, because that much stone would be too heavy for the walls to support.

The devils who'd guard it from the air are mostly being pressed into moving water around instead.

Stristyko thinks he's waited long enough, and that they're as distracted as they're going to get.

He gives himself another invisibilty, before teleporting into the sky above the cathedral, and featherfalling into the Forbiddance unharmed because he, too, is Lawful Evil.

He'll unload his cargo of incendiary skeletons onto the rooftop when he reaches it, commanding them to run in many different directions.

You can't be here unopposed.

They'll fight you if they have to, even if they're not all entirely sure where you are.