Flying City Defense

[TeslaJr]

My epic level Netherese fanboy wizard recently got the OK to rework Proctiv's Move Mountain from Player's Guide to Faerun so that it scoops up a rough semisphere of rock ~30miles in diameter, which he is going to use to raise our city. Once it's up in the air, it's going to need some protection, as well as flying city-to-ground assault capabilities. My character is trying to bring back the full glory of the Netheril Empire (with him as the God Emperor, of course), and is going to use this city as the new capital for the Empire, so it's going to feature a LOT of magic, as well as some stuff from the Tippyverse (Magic Traps of Create Food and Water, Fabrication Traps, etc.).

For the defenses, I am going to set up a Mythal (Lost Empires of Faerun) over the city, which will probably be one of the main defenses. Other than that, I'm probably gonna set up a Weirdstone (PGtF) inside the city to prevent teleportation into and out of it (except wish/miracle). There will be a teleportation circle outside of the radius of the Weirdstone connected to another teleportation circle on a platform that can be raised and lowered from the bottom of the city, so getting up to the city won't be a problem (plus, we have an airship hangar). The city itself will be surrounded by Walls of Iron cast with the Invisible Spell metamagic (gotta have that good view). Around the edge there will be a minefield of auto-resetting magic traps, though I'm not really sure what the most effective spell would be for these. At some point I'm going to craft a few Stone Colossi(Epic Level Handbook) to protect our gates, along with some semi-intelligent Spell Turrets (DMG2, IIRC). I'm betting there's a bunch more that can be done, but that's what I've got (which doesn't include the large number of soldiers [wizards, fighters, clerics, etc] that protect the city). I've still got about a 10mile radius that has nothing in it defense wise.

I have considerably less for air-to-ground assault capabilities. I was thinking of altering the magic ballistas from Heroes of Battle to have a longer range, but that's about it. Maybe chutes carved into the earth to drop casks of alchemist's fire.

[NoACWarrior]

First of all - how much gold do you have for air defense?

If a lot then a command word 5/day cartridge loaded into a cannon of magic missile would be feasible on every rooftop. I don't know if you can manage it, but automate each with a single nanite and give specific rules for each nanite. For each and every 10 ft square space in the 400 square miles you could have a great low air defense grid (any living thing within 100 ft of any building goes poof) for 111,513,600 x 1800 = 200,724,480,000 gp for 5 shots a day requiring 111.5 million nanites.

You could also get Fireball / Scintillating Sphere cartridges as well - but these will cost 15 times as much as the magic missile, but provides a great amount of air coverage (think of these like flak cannons). You may also need to man these flak cannons instead of using nanites, but hey a commoner is pretty good at battlefield knowledge when controlled by the DM. You get 600 ft of range per flak cannon, and get pretty good volume on a single blast.

For other airships, Fireball and Scintillating sphere (and magic missile) may simply not be enough. You could pick up Blistering Radiance cartridges as well - but these will cost 28 times as much as magic missile or twice as much as a fireball. But you get the bonus of having an AoE DoT which damages the attacking airships, heck you could light up the sky for 7 rounds at a time making anything in the clouds burn up. These could be your main AA guns and have a range of 680 ft.

For single smaller targets, Melf's acid arrow could do the trick, it allows objects and constructs to be targeted too, and only costs 5 times more than the magic missle, but cannot be nanited, and even lvl 1 commoners shouldn't be using this cannon as it requires a bit more BA to hit things. These could be your light machine guns and have a range of 520 ft.

I would put all the flak cannons on important structures for commerce and military mobilization while protecting the general public with the AA cannons and some common light machine guns at each police station.

but 200 billion gold.... yikes...

[Dorian Gray]

I think the traditional method of city defense is massive numbers of shadesteel golems. You could purchase a number of hurricane's eyes (75,000 gp) or tornado's eyes (90,000 gp), which create hurricane/tornado force winds around the area they encompass, but each one only covers 12 stronghold spaces (perhaps 100 by 100 feet), and they have to have all the areas touching for the tornado to go around the edge, and that would cost a lot.
For a bunch of stuff that would help, try to find the stronghold builder's guide. It has a lot of fun stuff, as well- the Ballista Bolt of Healing, or the Explodestone (aka the stone sorcerer).

[TeslaJr]

200,724,480,000 gp
Yeeaahh, that's a little out of my price range

[WeeFreeMen]

Well, here's what I can think of.
__________________________________________________ ____
This assumes
1) Your DM is going to flip a desk and/or gives you enough time.
2) You and your party are epic level casters.
__________________________________________________ ____
Step 1) Have the aspiring "God Emperor" gather a few hundred followers (300 should be Ok) and load up your new-found capital Noah's Ark style. Now you have a workforce as well as people to train.
Step 2) Create a pocket dimension in which you can move the Capital. This dimension should have its time move at 1/100th that of the Over-world. Spend the equivalent of 1 year in-game time (100 years over-world time) training your new-found NPC "Experts" or "Initiates".
Step 3) Start building your tippy-verse to feed and maintain your capital. Start slowly brainwashing your acolytes so that you start being worshiped. Once you have enough followers (Through world domination) you can achieve Demi-God status.

With all the extra helpers the crafting should be easier/cheaper on you.
As mentioned earlier, Magic Missle turrets are awesome. The whole "never miss" is very useful, and when there is 100 + of them, even epic level monsters have to be careful.

Another defense Mythas you could cast is a basic Mirage spell/wall around the entire City; making it invisible to the naked (non-magical eye) but blindingly bright to those with True Sight.
Alternatively, have each member possess a Guild Emblem or Capital Passport of somekind; register it to the user and use that as the only means of incoming traffic.
Effects like the epic spell "Dire-Winter" will keep out the low-level trash.
A series of Perma-ForceWalls or Cages over your cities head could prove useful vs. barrages/bombings.

And as mentioned, the Stronghold Builders Guide really is awesome for these kinds of things.

[NoACWarrior]

ok lets trim that superior defense budget down a notch then.
If you watch anime - pilots love song has a flying island which has very little air defense and relies solely on fighter squadrons: the shade steel golems can be used for that.

If you want ground based air defense you'll require a bit more manpower than expected, but hey you run a city so employing people on air-defense is a good thing.
Don't get any of the magic missle turrets - they are great for an airship or a well funded fortress, not for a flying island this big. Also if you are making the turrets in your city, it will only cost half as much.

If you want 100% coverage (or near that) without much overlap, you can place a single turret up every 400 or so feet, this will give maximum 400-700 ft range, with the defense canopy bottoming off at around 300 ft off the top of a building. This will require around 175 turrets per square mile, or otherwise around 300 square miles and 52500 turrets.

If you have only around 33% occupation of land, with the rest of the land being farm land what not, it becomes a manageable 525 million GP for 17500 turrets (average 30k per turret).
If you only cover the "important areas" which take up only 10% of your total land, then it becomes even cheaper at 157.5 million GP.
If you cover "bare essentials" which take up 2% of your total land, then it becomes 31.5 million GP.


I personally wouldn't advise anything less than all the occupation of the land - enemy troops can land in there and kill your people making you less effective as a city.

Alternatively if you don't want to put the turrets on the top of people's homes and on city hall you can make taller towers to mount them in, allowing for less of them because you can get greater coverage. For 100% coverage you can place a turret every 800 feet, this will require around 44 turrets per square mile, or otherwise around 300 square miles and 13200 turrets.

For only occupied land, the cost is 132 million GP for the 4400 turrets on the 100 square miles.
For only important areas, the cost is 39.6 million GP for the 1320 turrets on the 30 square miles.
For the bare essentials, the cost is 7.92 million for the 264 turrets on the 6 square miles.
(prices are not halved as stated for turrets made domestically)

Base turret has 5 uses per cartridge per day. Put the Blistering Radiance on areas prone to attack.
Fireball / Scintillating Sphere cartridges - 27000 each
Blistering Radiance cartridges - 50400 each

[ellindsey]

Attach Magic Mouth spells to your spell turrets. Have them say things like "Are you still there" and "Could you come over here please?" when they detect an intruder.

[atomicwaffle]

Control Weather, or an Orb of Storms

Wind, Hail, Thunderstorms, Fog, Cold, Rain, Snow

Storm of Vengeance

[Elkad]

A tarn net (or sky net) or whatever. Plain old mundane cables, forming a net over the city. Turn em invisible or whatever if you don't want to block the view. So 10,000 mooks on flying mounts can't zerg your city if the magical defenses get dropped.

[pwykersotz]

To prevent gaseous attacks, put small portals to the elemental plane of air just inside the invisible walls of iron. You can steal the secret of making them from the Drow, they use the same setup in Maerimydra. This keeps the air inside fresh and external conditions won't matter at all.

[animewatcha]

Forgive me, I got lost in some of stuff in this thread already. When I think of Flying City Defense versus a ground-city, does the flying city have a crapton of ground 'underneath it'. Think like your typical BBEG flying fortress in video games. If the ground is big enough, can't the city 'temporarily' drop on top of the opposing city as an attack.

[TeslaJr]

This particular flying city is atop a rough semisphere with a 15 mile radius, so yes, there's a crapton of earth and rock underneath the city. I think dropping the earth would wreck my city as well, or at least damage it. Besides, I want the cities to be intact so that I can use them.

[Arcane_Secrets]

Around the edge there will be a minefield of auto-resetting magic traps, though I'm not really sure what the most effective spell would be for these.

How about heightened flesh to stone? Not only does it force attackers to dodge the statues of their own troops as they plummet, but if there are any attackers on the ground they get pelted shortly afterwards.

[Ravens_cry]

How about heightened flesh to stone? Not only does it force attackers to dodge the statues of their own troops as they plummet, but if there are any attackers on the ground they get pelted shortly afterwards.

Doesn't affect undead or anyone else immune to fort saves that don't affect objects, and it will be much less useful against anyone with spell resistance.

[animewatcha]

This particular flying city is atop a rough semisphere with a 15 mile radius, so yes, there's a crapton of earth and rock underneath the city. I think dropping the earth would wreck my city as well, or at least damage it. Besides, I want the cities to be intact so that I can use them.

Mending. Fabricate. *insert other spells for repairing non-magical stonework here*

[Andion Isurand]

Considering the earth's troposphere extends to an elevation somewhere between 6 and 11 miles, where the air averages about -40° F, where jet streams blow can blow at speeds in excess of 100 mph and the thin air sustains little more than bacteria... the planet of Toril might possess some mighty harsh conditions to contend with, without additional magic, if the hemispherical foundation of your city is 15 miles tall/deep.

I would consider using a mythal to help maintain temperatures, atmospheric pressure, govern wind speeds... using a customized factor of being centered on a mobile capstone that can be moved using the mythal itself.

Last February, I did some work on just such a mythal, albeit much more modest with a 2 mile radius hemisphere of stone, and a 3 mile mythal effect radius. Be sure to check out all the pages I drafted for that month, to get an idea of where the additional participants for casting the Mythal actually come from.

http://magerune.blogspot.com/2014_02_01_archive.html

[Gavinfoxx]

Have you read my handbooks and some of the threads they link to?

IE:
https://docs.google.com/document/d/1aG4P3dU6WP3pq8mW9l1qztFeNfqQHyI22oJe09i8KWw/edit
http://www.giantitp.com/forums/showthread.php?222007-The-Definitive-Guide-to-the-Tippyverse-By-Emperor-Tippy
https://docs.google.com/document/d/14zilT4WGOyHM0AfpG4-GmD2FkgDg1HZ9HC1cTleQHds/edit
http://community.wizards.com/forum/previous-editions-character-optimization/threads/1128391
http://www.giantitp.com/forums/showthread.php?320604-What-is-so-great-about-the-shadesteel-golem&p=16637717&viewfull=1#post16637717
https://docs.google.com/document/d/1Z9NJIs751Af3i0IEIJwCkIp9H9YFiZYZ7u-wmYVaheI/edit


Mostly, the best defenses will be 'capable bipeds to defend it', more than anything...

[TeslaJr]

I've read a few of those links, and I've got to say they're nice. Common foot soldiers won't be a problem, trust me. I forget the actual number, but I have a standing army of around a few hundred thousand.