Do we have to?

Yes.

She Plane Shifts the important people still left in her party, and a 5th-circle wizard teleports her to the agreed secret observation spot chosen beforehand. She knows the rules and intends to follow them. You're not going to catch her out and exposed.

The defenders aren't doing so great on the city walls.

They'd like to retreat to Fort Constance, atop Admirality Hill which overlooks the bay, if that's okay.

We've actually got a substantial force on the streets behind you, cutting you off from reaching Fort Constance.

There are few fast ways to move large numbers of people around the city.

The natural choke points have been filled with rubble. A 5th-circle Transmute Rock to Mud can turn a square of pavement 30 feet to a side into impassable mud 10 feet deep. The bridges are rigged to self-destruct behind the defenders. Flammable rubble is piled anywhere the defenders think they'd prefer things be on fire.

With three days, magic can turn a city of several square miles into a sea of obstacles.

If you're at the wrong end of the city, the fastest way to Fort Constance would be to climb back over the walls, walk around the outside, and then climb over again somewhere closer.

The defenders have shortcuts, prepared in advance. They'll collapse the shortcuts as they cross through them, and shoot arrows as they retreat to buy distance at a price in lives.

They weren't expecting this many troops behind them, though. Many aren't going to make it.

He's old now, older than he expected to reach.
His body is frail and his bones hurt, though at least he still has his memories and his eyesight and a good sense of humour.

He's too old to start again somewhere else, he thinks.
He's been a burden on his children for years, already.
He didn't leave Augustana when they said the ships were going.
He tried to sign up when they asked for fighters, but they said he wasn't a fighter and honestly they're not wrong.

He's hiding behind a table, at a corner of what was once his son's workshop, before they fled.

He doesn't take handouts. He paid a fair market price for it. That's what honour is. It cost him most of what he still had. He made his son take what was left. That's honour, too.

The soldier bashes in the door. It was barely much of a door to begin with.

They're not supposed to be looting while there's still defenders to kill but maybe someone is hiding here, he can tell himself, and maybe it'll be a girl and maybe she'll put up a fight and technically that'd make her a defender.

He's pretty sure that'll hold up under truth spell. He's trying to remember that he's coming in here hoping to find an important enemy combatant to slay, and not for any other possible reasons.

He reads the rune he stuck above the door, from a distance, as the soldier forces his way in beneath it.

He thought he was far enough away, and that the table would be enough protection. He wasn't. It gets him too.

He gets Chaotic Good, like most of his friends did.

I figured it out.

Hypothetically, if I cast a Control Weather to cover the city in torrential rain, what would happen?

I'd dispel it from my secret observation spot.

Then you'd have to be within 2 miles of the city. Almost certainly inside the city walls, in order to be within reach of most of the current combat areas for any smaller but still large AoE effects someone might produce.

No comment.

The actual buildings part of the city is still mostly controlled by us. There's no safe bets about how the line of control might change over time.

You could be high up in the air, casting useful spells at a range that won't give away your location or who is casting them. That hasn't been happening. Our remaining dragons have been trying to provoke a powerful caster into dispelling them and it hasn't happened.

You're saving your spells for when the battle is progressed to Fort Constance because then your remaining enemies will be more tightly packed together. You'll still want direct eyes on the battle, and a way to support your troops. You'll want them to have good resupply options within the city, too, instead of having to carry everything they might need over the walls.

If we think about the very start of the battle, the first thing was that some Sarglagons used Control Water to destroy the docks. They're reasonably powerful devils, and you needed several to produce that big an effect. You must have spent quite a bit on them. But they're much less dangerous outside the water. So they're just sitting in the water and nobody wants to go in and fight them. They're mostly being irrelevant to the battle. Just wasted units.

Nobody on our side wants to go into the water and have to fight the Sarglagons. The Sarglagons have pulled in enough dirt and muck and rubble to make the water difficult to see through. They're peaking up above the muck periodically. Maybe to look for any targets too close to the water edge or maybe just to check in on the battle generally. They disappear back down again before they can be attacked from the surface, and then pop up later somewhere else.

You're hiding under the water with Water Breathing or something like that, and the Sarglagons are reporting what they see to you. You started in the Fresh Harbour to be closer to most of the action, and you're planning to swim into the Salt Harbour as the attack progresses to be closer to where the final showdown will happen at Fort Constance.

If any of your commanders need something from you during the battle, they'll just jump into the harbour and ask a Sarglagon. You've probably got a bunch of supplies down there, under the water. You probably Gated them in nearby yesterday. You get free supply access across half of the city, because nobody wants to fight Sarglagons and we're all assuming if we stay on dry land they don't matter.

How in the Abyss

"An invisible creature displaces water and leaves a visible, body-shaped “bubble” where the water was displaced". You'll be using Invisibility Bubble instead, which hides this flaw by creating a bubble of invisibility that hides both you and the optical effects of the water you displace.

Invisibility Bubble has a small flaw of its own: "Other objects and creatures within the bubble’s space are also invisible while they stay in the space".

You'll have Mind Blank, which would stop See Invisibility detecting you and every object in your possession. It doesn't need to detect you, though. It just needs to detect the invisible small objects and fish that might drift or swim into the same 5-foot cube as you, because they don't themselves have Mind Blank. The difference literally does not matter at all except if you're trying to use Mind Blank to prevent someone seeing through your invisibility. None of the magic books you've read would care to mention it, unless they were specifically intended for fighting 9th circles.

The channel between them is only around 300 feet, at its narrowest. True Seeing has a radius of 120 feet. Two small water elementals with True Seeing can hide in the same muck you're hiding in, but they'll be better at it. When the battle progresses towards the fort, you'll move over through that narrowest point, having Sarglagons move up the supplies as you go. A canny observer will still be able to spot you.

You're at this exact spot -

Is that a water elemental?

I don't have any Time Stops left, but you don't have a crown.

Dispel Magic, Spell Resistance.
Quickened Dimensional Anchor.

Empowered Touch of Idiocy, Maximised off a rod.

Quickened Dimensional Anchor.

I didn't bring any overly expensive magic items to this fight.

You're not getting my soul.

She ends the Possession, cast off a scroll at great difficulty.

It'll take Aspexia a hot minute to recover from losing her surrogate body, and have new abjurations put in place, yes?

She doesn't have any wizards with free 8th circle slots to spend on yet another Mind Blank. Is it worth a scroll? It's probably worth a scroll. She needs a high-level wizard who can teleport back to Egorian Westcrown and help cast the scroll for her.

Great. Then she gets to attack some infantry companies. You should know them by now. It's those spells than end in Fog and Cloud and the like.

She's got Metamagic rods, too. Technically the university owns them, she's not personally that rich, but they'll let their Provost borrow them for this kind of thing.

They've taken really a lot more casualties than they expected to, by this point. A lot of the city is rigged to explode. They have mostly now learnt the important skill of how to consciously choose not to read anything even when it's right in front of them.

It's an exhausting slogging match to get up to the fortress itself. Still, soldiers follow their orders, not their self-interest.

They only prepared the one batch of clever tricks for scaling walls.

They've got another batch of walls to overcome, and would like orders from their queen as to how best to achieve that. Does anyone know where she is?

They'll stop here just outside of line-of-sight from archers.