Energy Transformation Field and other magical defenses

[Alleran]

My group of players have decided to settle down (so to speak) and create ourselves a stronghold from which we can launch further adventures, demand tithes from the surrounding countryside, and so on and so forth. Of our group, I am the party wizard (it's been a long and welcome relief from DMing, which I usually wind up doing myself), and have been chosen to create many of the magical wards that will protect our stronghold from assault. For the record, I'm an 18th-level wizard (Well, Wiz 6 / Loremaster 9 / Archmage 3, technically, but that's just splitting hairs), so I have a lot of power at my beck and call if need be. The other party spellcaster is a 17th level cleric, but for IC reasons he can't help design this with his own spells, so it pretty much comes down to me (though the others are contributing plenty of the party wealth to getting this set up).

At present, I've used things like the Genius Loci spell, Halaster's Teleport Cage (getting that one was an adventure in itself...), Greater Familiarity of Place, and managed to get a Secure Cavern effect going, before hunting for some other spells to put into place. I'm trying to avoid magic items with a radius of effect at the moment, and am using spells except where I can't get out of it. We've also got a mildly-positive aligned demiplane for some Fast Healing action, but need the big castle (of which I have part as my own tower... gotta love towers) for an outward show of force.

The spell I'm looking at now is Energy Transformation Field (Magic of Faerun p.92). Essentially, any spells cast within the field instead power said field, until it fires off a predetermined spell at a certain point inside the field and expends all the spell levels that power it (e.g. if it were set for a meteor swarm, then it would absorb 9 spell levels worth of spells, then target a meteor swarm spell at a fixed point, then wait for the next nine levels). You need a Disjunction to take it down (or a limited wish or wish) Enough of these, I am thinking, should help deter would-be wizards (and even potentially give pause to higher-level ones) who think of attacking, but I'm not sure what spells to store in the field.

Any suggestions on good ways to make use of this spell would then be much appreciated.

Any other good tips and tricks to use spells in order to create a well-defended base of operations would be helpful too. We do have the limitation that the Stronghold Builder's Guide and a lot of the Draconomicon "stronghold" stuff is almost entirely off-limits except for on a case by case basis, but the DM is willing to listen to requests, and is generally reasonable about it.

[iDM]

Fog Cloud or Mirage Arcana, to confuse the enemy? Maybe some sort of mass confusion?

[kalkyrie]

Antimagic Shell, or Energy Transformation Field (if it's possible to recast) might be interesting.

[Urpriest]

For the spell created, "Create Food" is a good one.

Though on second thought, I'd use it as a trap for enemy casters. Perhaps two fields with, say, Forcecage and Dimensional Lock? Or Teleportation Circe? Either way, catch whoever dares to cast in areas they aren't supposed to so you can deal with them later.

[The Glyphstone]

Temporal Stasis or Imprisonment would be the best choice for that route, since they actually incapacitate rather than just immobilize.

[Jack_Simth]

Shades (Trap the Soul). Ranged, Will save or lose, no real way to be actually immune. Oh yes, and you don't wait for people to trigger it. You set some kind of automaton repeatedly using an Immovable Rod, Rod of Wonder, or some other at-will device (as it absorbs those too). Just make sure it's not a living automaton, and you're pretty much set.

Oh, and for your living areas, yeah, use beneficial spells. Get a Ring of Greater Spell Storing, have your Cleric buddy put in Heroes' Feast, and make an Energy Transformation Field (Heroes' Feast). Ditto for Mass Heal, and any other buffs you'd like. Then walk around clicking on an Immovable rod to power them whenever you want them.

And it'd be really, really useful if you could convince your cleric buddy to Forbiddance up the place....

Edit: Oh yes, and you'll also want some spells for when you've got non-living invaders. Summon Elemental Monolith is always fun.

[Andion Isurand]

You could also use Replicate Casting (SpC) to reproduce 8th level and lower spell effects (such as Forbiddance) from outside your class list by first casting those spells from scrolls via your UMD skill.
I would also recommend Mage's Private Sanctum and Hardening (for doors and walls).

[Alleran]

Though on second thought, I'd use it as a trap for enemy casters. Perhaps two fields with, say, Forcecage and Dimensional Lock?

I've got the Teleport Cage effect to block or at least royally mess up any teleporting attempts, though a Forcecage is an interesting proposition that hadn't occurred to me.

I was mostly looking at area-effect spells of a moderate level, because if the spell it fires off is lower level than the high-end stuff, it doesn't take as much time to build up the necessary spell levels to cast it when potential enemy spellcasters are sticking their noses where they're not wanted.

And it'd be really, really useful if you could convince your cleric buddy to Forbiddance up the place....

Yeah, like I said, he has IC reasons that prevent him from casting spells like that. Any spell that would involve "settling down" in general, so if it lasts more than a couple of days or so, then it isn't happening, unfortunately. He's just donating wealth and some of his spell scrolls to the cause. I could try duplicating Forbiddance via a wish, I suppose, but I don't quite know how it would interact with the Teleport Cage (which is from City of Splendours: Waterdeep).