I have a castle in a campaign that I'm building using the ultimate campaign rules, and it has expanded to quite a little citadel.
It has barracks, a throne room, kitchens, guard posts, a protected gauntlet, a wet moat around it, even an orphanage (complete with school room!) amongst many other things. I have over 200 armed soldiers at my command (some from leadership, others from teams from the Ult Camp ruleset).
I also have a skilled wizard cohort with a stocked wizard's tower on the premises. (scrying room, library, etc) He is lvl 10 with permanency, and a wide spellbook.
Now, I need Ideas/suggestion for RULES SUPPORTABLE protections to place to keep it secure. Assume any 6th and lower spell is available, and 50,000 to spend. Don't think only of magical means, sometimes mundane ones are just as effective (like 3 alternating guard rotations, blindfolds for entering strangers, etc)
Current ideas (not extensive, just providing spring-board concepts for further suggestions)
Permanent Symbol of healing in the infirmary.
Permanent Dancing lights patrolling around the outside of the wall (akin to guard lights)
Decanter of endless water keeping a moat full
Wizard's expensive materials are in a completely sealed 20x20x20 room under the castle, encased entirely in stone, with no 'secret' passages (teleport/earth elemental/etc only accessible means)
A gauntlet with several "explosive runes" wallpapering it, requiring anyone passing through to have an escort and be blindfolded.
Let's see what ideas we can come up with! Thanks for the help!
Continual Faerie Fire around all exterior walls, roofs and entrances. Limns the invisible, glows in the presence of magical items and spells. Very useful effects to have!
Bound earth elementals whose only duty is to prevent tunnelers/burrowers.
Definitely Forbiddance to stop dimensional hijinks. Private Sanctum is there to stop divinations and scrying. Proof against Teleportation would probably be nice as well.
A Prot/Evil zone and an a permanent anti-magic shell somewhere known and useful, such as just inside the main gates, for suppressing mental control and possibly identifying the possessed or shape changers.
A 'trap' that casts CLW once/day per person. They can just stumble through it for an automatic heal. If it's in a known courtyard, might even be accessible to the public.
A shrine that casts Magic Weapon at 8th or 12th level 1/day/weapon laid before it.
Stores of holy water, elemental fire/acid/lighting/frost, for those special friends come to visit. Nothing says welcome to a visiting red dragon like 50 vials of alchemical cold to the face.
Siege Engines that can be moved around readily and provide their own ammunition.
The highest tower casts Eyes of the Eagle on whoever stands on the top of it, letting them truly see for long distances.
Feather Fall affects anything heavier then 20 lbs passing the castle's walls in the air, stopping all forwards momentum and making them drift down to land just outside the walls. Thus bombing and throwing rocks at the castle doesn't work well, nor can it be overflown.
Dimensionally expanded rooms or marshaling yards using Distance Distortion to best effect, or similar things.
Make sure the walls are stone/dirt/stone layered, so it takes at least 3 passwalls to get through (standard construction, actually). If you add a middle layer of honeycombed rock, they are basically impassable that way.
==Aelryinth
There quite a few spells you can Permanency to good effect. Why have water in your moat when you could have a Stinking Cloud, for example.
.... caster limit for my permanency is 12 atm, (soon to be 13) and I've got a few permanency spells in, or planned, already.
As far as stinking cloud... roleplay reasons kind of make me NOT want to surround my home with that =p Iomedae values cleanliness
Alarm for my bedchambers/other key areas.
Dancing lights x2, rotating around the exterior of the castle
Mage's private sanctum (next level) (around interior keep)
Symbol of healing on a statue of Iomedae, with triggered magic mouth for anyone approaching that says "Accept the healing of Iomedae and continue your fight against the devils that plague our realm"
Wall of forces wrapped around the castle to prevent siege engine damage/pass wall/etc.
Wall of Force has a VERY low area of effect (go look at it). You're going to spend a LOT of money on Permanency if you have to chain together walls of force.
Oh, a Lyre of Building, so you can fast repair damage to your building structures. You'll need someone who can play it, too.
==Aelryinth
Well Ivy growing up the outer walls to prevent Passwall (since that works only on stone). EDIT: Whoops missed the stone/dirt/stone, that works too & maybe better.
Then you could coat buildings/walls in lead (or more expensively gold) to prevent scrying.
Summon Monster Traps are always fun. Depending on the amount of time you have, and the gold, having a bunch of Huge Elementals spawn near a gate without a password can start a fight off on a fantastic note almost immediately.
Beyond that, never underestimate the stupidity of lots of mundane equipment. Having 200 guards throwing 200 acid flasks at the same time? Awesome. And easy to hit given that even just hitting a square is almost impossible to miss, and 200 guards throwing that many flasks, and even if only doing 1 point of acid damage, can kill quite a few creatures very easily (except anything with acid resistance, but who ever expects that sort of defense?)
Get yourself some Bards. Even a level 1 bard giving a vast majority of guards and party members +1 to attack and damage rolls is fantastic.