The Flagship is much faster than him, when it wants to move quickly. He cannot swim under it always, but he stays on deck for support, and watches the waves.

He has zero hope of seeing anything.

He can totally keep up with the Flagship, if he wants to.

He swims at 90 feet a round.

He has 14 Strength and 4 Intelligence.

He considers 43 pounds or less to be a "light load".

He is "holding", more like pushing, a bag of 6 smooth metal pebbles with him, through the water.

He likes water. He is pushing them in a straight line.

What is he supposed to do again? Oh right, the boaty.

The ship is moving forward at close to 90 feet a round. A pebble is "spat" out above the waves in front of them, at close to 180 feet a round, relatively speaking.

Water Elementals aren't profficient with throwing rocks. It'll have pretty bad aim, because of that. On the other hand, it's aiming at a Warship. AC=2.

The Small Water Elemental speaks a command word, in Aquan. Water Elementals speak Aquan, did you know? The metal pebble expands before they hit the hull.

It look more like a steel-reinforced barrel when it hits.

Velocity is conserved even as momentum isn't. If that weren't the case, orbital mechanics would make Shrink Item a superweapon in the opposite direction.

The Warship takes 30 damage. There's a hole. It's not gonna sink or anything.

The metal support cracks open on impact, as it smashes it's way through, and the gallons of kerosine oil contained inside explode as their exposed to air and ignition sources.

It's not the top-shelf stuff. They're going for quantity here, not quality.

The splintering force of the impact sprays it everywhere as the ship combusts.

She's been in fights before. She's not going to think anything stupid. This is clearly enemy action.

She commands the Repair Wizard to cast Make Whole, twice.
She commands the marines to put out anything on fire.
She commands the Sarglagon to hit the waves, and the larger flying devils to hit the sky.
She commands her flag officer to signal their escorts to pull towards her, and expect a fight.

They're Asmodeans. They obey.

She still has no idea what they're fighting. See Invisibility? Sarglagon has that, would have noticed if that was it. Cast it anyway. Send for below deck to check what the damage was.

Somethings in the water. What else can I deploy there?

They'll start throwing their pebbles too. Bonus points for how many seperate holes you can make.

lesser Planar Binding is a perfectly respectable spell.

Is it going down yet? It looks like it.
Oh it's a Sea Devil, gotta bail.
We have 90 swim speed, you can't catch us.

There is a lot of water in the ship now. It's competing with the fire for who can wreck stuff the fastest.

This isn't a new threat. We've got options here.

Rod of Flame Extinguishing. A variety of ice and water spells.

We can put the fire out if we want to.

But with so much fire, they can't put it out all at once. A flame left will reignite the fumes and leave them back where they started.

Yeah I think we're going down.

The ships not out of hitpoints. It's just sinking and burning faster than they can fix it. It has too many holes at water level.

It's own forward momentum tears at the structure, as the still open sails are pushed forward against the resisting sea, and the smoke of gum and wood clogs the air.

Druvalia Thrune has a choice to make.

Plausibly, if they stay and work with what they have, they could recover the situation. But there's no reason to expect the enemy doesn't have more planned.

On the other hand, there is really a lot of mission-critical equipment on board. All logs of the subordinate fleet are kept here, with her, so she can command them.

Expensive equipment. Nautical maps. Magic items. Herself.

They've already used their Shells of Sending for the day. It's the evening. It'd take 10 minutes for a regular Sending, and they don't have infinite time.

She can call a Mirror Sight, to teleport to another ship. It would also take 10 minutes, though. They'll want as much of it as they can into bags of holding, to quickly teleport out if needed.

If the other ships survive, it'll be easier to save things by casting Fly and moving them across.

"Officers, secure up our magic items. Don't want any of them falling into enemy hands.
Devils, Sea-Sworn. If anyone even thinks of surrender, kill them. Hell will sort them out.
Men, defend your ship.
I'm going to Fly over to the Pearl. They're turning our way, it'll be a minutes.
If we're going down, she'll be our rescue."

You thought we were fleeing?

We're going to the other ships too.

We've got a swim speed of 90 ft. We'll get there first.

Okay yeah this is bad.

It's clearly water elementals, and they're controlled by something smart.

Those boats from up ahead will be it. They don't look fast or strong.

If everything that can Fly chases them down, we can make this summoner regret themselves.

I'll match their speed and stay out of range, how far will they chase me?

On second thought, lets teleport out.

Everyone above lieutenant still on the ship, get in my quarters.

Some of the wizards, grab the scrolls we've got, we'll rescue as many worth rescuing as we can.

The Water Elementals catch up to their Master, at his leasurely pace.

The other two aren't sinking yet, just damaged. It's not like they can flee from him.

He'll give the bound outsiders a few more bombs, enough that their quest is completed. Once it's done, he pushes the engine back on full throttle, and they split up into different directions.

He just had to wait for his buddies to show up. He couldn't have done enough damage by himself, not until he hits 6th circle. It didn't take them long, once he found a target and they say on Track Ship that he'd stopped to wait.

He can summon some more and do it again tomorrow.

"So you're saying I need, five 5th-circle wizards, and
... 75,000 gp in diamond dust?"

"Yes, it's the cheapest strategy as far as I can tell. I've checked.
And all you have to do for me is not tell anyone any of it was my idea."

"It doesn't have to go down exactly like that, you're the expert in Chelish doctrine here. You can use them supported with larger ordinary ships if you prefer, where you can handle supply.

But I'm pretty sure you'll want at least 4 of them.
I'm pretty sure you'll want to scout by air so you can find targets faster.
I'm pretty sure you should be intending to take most of their fleet out in under two weeks.
And I'm pretty sure you should hit the Flagship first.
It'll be most annoying to their command structure.

After that you can arrest their galleys whereever it suits you."

"And when they try to hit back? What you've described is defenseless."

"Then you just leave. You're faster than them.
The water elementals are slower than you, but also faster than them.
You can attack from outside their range while retreating.
Nothing can catch you unless you get cornered, make sure you don't get cornered.

If they send summons or devils, just leave."

"I'll... take this under advisement", he concedes.

Yeah, this looks like it could be it.

Is this the bit where I steal the new expensive propulsion devices?

What, they only work for the wizard who made them?

That's dumb.