Returning back to something a bit more topical and less likely to cause arguments...
Okay, now that I'm back home I can put some numbers down for the anti-Teleportation warding.
Using various buffs and Wild Arcana, we can raise Viserys' caster level to 28th while casting Forbiddance. It's a fairly intensive effort, however, so I wouldn't try to do it more than five times per day just to avoid using too many high level spell slots. At 28th caster level, the Forbiddance spells would have an effective caster level of 32nd for the purpose of resisting Dispelling attempts thanks to the Enduring Arcana effect on one of Viserys' rings. That means it is impossible for anyone at lower than 32nd caster level to Dispel them. At that point, only a Mage's Disjunction can bring them down, and even then each casting of the spell would only affect a 40 foot radius burst.
At 28th level, each casting will produce 28 60-foot cubes. Adding a password feature to allow our people access without being affected by the damaging aspect of Forbiddance increases the expense so that casting the spell would cost 14,500 IM. Using Ancestral Awakening to learn Widen Spell (since Forbiddance is 6th level, we can now cast a Widened version using 9th level spells or Wild Arcana), we can effectively double the number of 60-foot cubes from 28 to 56 without increasing the cost further.
A single use of Forbiddance in this manner would be able to ward an area equal to 12,096,000 cubic feet, or a space 420 feet long by 480 feet wide by 60 feet high.
If we increase that to 10 castings, it's 4,280 x 4,800 x 60 feet. That's 145,000 IM.
Then we add a subterranean layer, plus a couple layers on top of the original, increasing the total warded area to 4,280 x 4,800 x 240 feet at a cost of 580,000 IM, or 40 enhanced castings of Forbiddance.
To add extra height to the warding directly over the fortress itself, we could stack a couple more smaller layers of Forbiddance, four casting per layer, to extend it to 300 feet within an area 1,680 x 1,920 feet centered on the fortress. This would add another 116,000 IM, bringing the total up to 696,000 IM.
This would be very effective, not only preventing Teleportation effects over a huge area, but inflicting damage to anyone who doesn't share Viserys' Alignment or possess the proper password. Lawful Evil Efreeti, for example, would take 6d6 damage each time they moved from the area of one Forbiddance spell to another, since they share a Lawful Alignment with Viserys, while something like a Demon would take 12d6 damage each time they moved into a new Forbiddance spell, as they share no Alignment components with him.
That said, I would still vastly prefer to use a Weirdstone, even if it costs us a million IM (which would be 21.7 times the regular cost). It's a much larger area and we could defend the stone such that it would be impossible to target with a Dispel Magic or Disjunction spell.
Weirdstone
These innocuous-looking, fist-sized pieces of faceted glass are among the most highly sought-after items in all of Faerûn. Mages who like their privacy and evil beings who prefer to keep their plans secret are particularly fond of these items, and they often dispatch minions or adventurers to retrieve them.
When placed upon a flat surface and activated by mental command, a weirdstone floats about 3 feet into the air, glowing and chiming softly. While active, it blocks out all of the following within a 6-mile radius (including into the air above and the ground below).
- All astral and ethereal travel.
- All divination (scrying) spells.
- All conjuration (teleportation) spells.
- Any spell-like, supernatural, or extraordinary abilities, psionic powers, or the like that mimic these effects.
The weirdstone hampers only effects that manifest within its area. Spells or abilities activated within the weirdstone's area that target an area outside its 6-mile radius are unaffected. For example, a wizard standing right next to a weirdstone could cast a
scrying spell to spy on a creature more than 6 miles away, but she could not teleport across the room because the weirdstone blocks teleportation magic within its radius.
Strong abjuration; CL 20th;
Craft Wondrous Item,
dimensional lock,
nondetection, creator must be at least 20th level; Price 230,000 gp.
Source:
Player's Guide to Faerûn