Build a fortress to withstand almost anything

[Brother MacLaren]

If you're the DM, establish that certain materials defeat magic. If you're not the DM, ask him to make some neat rules along those lines. Ivy to block teleportation is a pretty cool idea (I think other Dragon articles have said gorgon's blood mortar). Lead will not only block scrying, it should also block passwall (can't go through metal IIRC). And if the materials needed to defeat powerful magic are rare and expensive, you haven't really broken the game (a king needs lots of money to buy materials rather than lots of money to buy the services of a wizard - what's the difference?)

Exotic gems, powdered and mixed with black pudding ichor, to make the walls proof against dragonfire. Powdered adamantite in the mortar to protect against earthquake spells, and a paste made from giants' bones spread over the stones to resist disintegrate. Salt encased in a narrow band of gold around the castle, preventing undead from passing through. Expand the established ways of countering magic without using magic.

The point is, castles are cool. If you have to introduce some new alchemy to make medieval-style castles more feasible, go for it.

 

[dead]

You have to protect it from Gaseous Form infiltration.

Spells like Forbidance can keep out Teleport, Etherealness, etc. but not Gaseous Form.

And of course you can't make it air-tight or everybody inside will suffocate. You'll have to resort to magic. I only own the 3.0 rules so maybe there is an Anti-Gaseous Form spell. I don't know?

 

[Zimri]

"Sir it took years but I am happy to report we have finished the fortress to your specifications"

"I thank you for all of your hard work and tireless effort"

*both walk over and stare at the impregnable fortress*

"I have a question for you Mr. Dwarven architect"

"Whats that sir ?"

"Well if it was made completely impregnable and I am on the outside how do you propose I get IN"

*both do homer simpson impersonations*

 

[Whimsical]

One defense that any site should have is Hallow/Unhallow. Normally a Dimentional Lock would be keyed to it to prevent teleporations and summonings from working inside, except for those you specify. Like you, for example. One of the nice overlooked element of Hallow is the Protection from Evil aura. This will keep summoned monsters at bay while making anyone inside the radius immune to their attacks. It also suppresses the effects of possesion or domination so casting Dominate Person or Mind Jar on the guy in charge of castle defense won't get the caster far into the castle. If you already have a teleport defense for the area, then setting the Hallow to Silence any spellcasters (except you and your spellcasters) in the area, or set it to Invisibility Purge the area can be good also.

The best part is that using Hallow is by-the-book, which helps prevent eye-rolling "yeah. sure. whatever." response from players. No need to create Plot Devicium to defend against those tricky powers.

In addition, even though one casting of the spell has its effects last a year, its duration is Instantaneous, which makes it immune to Dispel Magic.

Here's an interesting thought. If you successfully disbelieve a 3e illusion, then it becomse transparent to you. So, suppose you have Permanent Illusion of "black" or "huge block of stone" cast in all of your rooms and hallways? You and your posse know its an illusion so it doesn't affect them, but it would affect scryers and invaders of almost any sort, right? Including Fine-sized incorporeal invaders. This would be a cheap and effective security measure.

Anyone else have any other ideas for permanent or programmed illusions? How about illusions of bogus targets, such as yourself, placed in strategic places? Not only would spellcasters waste spells at it, but it could cause melee types to charge forward into a trap.

Oh yeah, don't forget to put Glyphs of Warding and Symbols all over the place.

Heck, just review all of the spells in the Players Handbook to rediscover those spells that would be great for a defensive setup. Like Permanency. The ones that most people ignore because they are impractical for an adventuring party to use in an adventure. Then check out the magic items in the DMG. A Stone of Alarm is cheap and can go a long way to defeating certain types of invaders. Have your spellcaster make a bunch for you. And you might as well have him cast Arcane Lock on all of your doors that also has mundane locks on them.

 

[CalrinAlshaw]

First off, how would having your castles walls lead-lined prevent teleportation. Is the air ABOVE the castle and BELOW the castle lead-lined as well? To me, if there is even 1 opening in the "lead lining" protection, it's useless. Other than that, what everyone else said.

Calrin Alshaw

 

[Paladin]

First, the Stronghold Builder's Guidebook is a great tool to use to build something like what you're wanting.

Here's a few of my suggestions:

For inacessability: underground is good, but how about using the top of a very high mountain, underneath the surface? You don't need magic to simply use natural (non-magical) camoflauge. If you're really trying to stay off everyone's radar, just use the mountain with minimal external building or changes (and camoflauge what you do change.) You could make the only entrance/exit be in the bottom of the lake that is at the foot of the mountain. That would also make enemy scouts think the stronghold was all underwater, and make the enemy waste massive amounts of gold/time/resources on planning an underwater assault. Use natural camoflauge underwater to hide the entrance/exit. Employ mer-people to act as guardians. Hold a massive reserve of water above the entrance/exit tunnel that leads into your fortress and should the enemy breach it, just "flush" them back out. If such a reserve were fueled by a portal to the Elemental Plane of Water, that might be a way to just keep doing that until the enemy gives up. Not much magic, just some good engineering. You could also use magic to freeze the water in the tunnel while the enemy is in there (or the whole lake when the enemie's force are massing.) You'd kill X amount of enemy forces, then they'd have to break out the until-now-un-needed fire magic to have any chance of getting the ice to melt. Once it's there, it's real ice, so no dispelling. Talk about frustrating! For real fun, place walls of force along the tunnel to stop their further advancement, once they deplete their fire magic. Then again disintegrating the walls of force would just unleash the new water being supplied by the portal...

When they finally figure out you're in (under) the mountain: rolling stuff down on an enemy trying to climb up is easy and no magic is really required. On the magic side, I can see a group of low level sorcerers using wands of flaming sphere to great effect too. Of course, your enemies will have to then fly up there, so having reverse gravity zones randomly spread out would be fun. It wouldn't take too many splats before enemy morale breaks. Once they do get up there, there's no entrance of course. One way to stop passwall is to layer the walls with steel (or other metal) bars since the spell can't pass through metal or harder materials. Since you're coating the walls with lead to hamper divinations, anyone wanting to teleport in would have to use greater teleport. Then, as was mentioned, you can use a permanent dimensional lock to stop that. Also, there's a teleport redirect spell from the Book of Eldritch Might that could be fun to purposely use on "weak" areas of your defenses.

Optional: You could build your fortress in a dead magic zone (assuming you have those in your world.) That would negate the magic stuff I mentioned, but it'll negate your enemy's magic too.

 

[MarauderX]

Some more things to consider...

Is the fortress to be used for business and markets during any normal season? Will the amount of income and number of inhabitants (defenders & support peasants) be related to the production from surrounding lands? This was typical, or is it like LotR:RotK where the opposing army shows up on a neatly mowed lawn, free of any farms, outlying structures, towns, and other tertiary things that might be there. If not, then you are in the clear to build your castle anywhere, and if your army needs to eat have clerics produce it. Details, details.

If you do have worry about production, such as with Fields O' Blood, the opposing army might pass your mighty castle by and raze all of your resources instead of bothering to lay seige while you are all turtled up. Go ahead, try to wage war now that you have nothing to eat for the coming winter.

I don't think you will be able to stop persistant individuals, as disguises could be made to bypass any magical alarms into the place. I'd concentrate on just stopping a mad rush of an army pouring through the gates instead.

 

[Grishnak]

"Sir it took years but I am happy to report we have finished the fortress to your specifications"

"I thank you for all of your hard work and tireless effort"

*both walk over and stare at the impregnable fortress*

"I have a question for you Mr. Dwarven architect"

"Whats that sir ?"

"Well if it was made completely impregnable and I am on the outside how do you propose I get IN"

*both do homer simpson impersonations*

Lol that was brilliant but a good point

 

[Grishnak]

Or if the group will insist on trying to use magic to get in go for the wild magic effects from 2nd edition, they can be fun and make the players think twice about spell casting too much!
As for the castle who said it doesnt have to be air tight nothing was mentioned about living occupants A nice underground castle filled with traps, secret passage ways and say a tiny crack or 2 lined with an acid/fire/ice resistant coating for a vampire to use gas form to pass through but whilst not in use either strong winds blowing down them or area fills with flame / acid / ice to stop gaseous formed players passing through

 

[MerakSpielman]

Like a fortress carved into the shell of some giant turtle that just wanders around. Or maybe some kind of massive undead thing (so nobody can mind control it).

My campaign world now, quite suddenly, has a tremendously colossal undead sea turtle plying the depths of the deepest oceans, with an ancient civilization of Lacedons inhabiting a mazelike fortress carved into its shell.

Thanks!