I am writing a story set in a modern world where D&D magic works. Now, I also have a Cheyenne Mountain like set of facilities in my world, underground hardened military airbases. Obviously, you don't want any old bloke to be able to just use the Etherealness spell to waltz in through the walls and steal a nuclear warhead. You also don't want the enemy war leader to be able to see inside your war room. And teleportation would really be a security disaster. Could the unit's mages cast Mind Blank on every single one of the 570 staff of the base?

I had a couple ideas, using a multiple castings of or a homebrew larger version of the Forbiddance spell to cover every cubic foot of space inside the mountain and a similar method with Anti-Magic Field around the boundaries. This seems to block anything short of divine intervention, but I was thinking of asking you folks here about ideas as well. Would my idea work? Do you have any suggestions? Perhaps a magic item that could do the protection?

I'm not concerned as to which version the spell/item comes from.

  • \$\begingroup\$ Hi Jazzyamx - I am voting to close this as it stands for now because you will get answers all over the place. I suggest that you break this into several different questions, such as protection from divination, protection from teleport, mass mind blank, etc. Doing so will attract more direct and high-quality answers. \$\endgroup\$
    – Kirt
    Commented Sep 5, 2020 at 3:23
  • 1
    \$\begingroup\$ There are already questions covering anti-scrying and anti-teleportation; combine with elements for making an area suitable for secure legal proceedings. Then, with all that in mind, maybe this question can be edited to ask about the gaps? \$\endgroup\$ Commented Sep 5, 2020 at 3:31
  • \$\begingroup\$ Welcome to RPG.SE! Take the tour if you haven't already, and check out the help center for more guidance. As written, you seem to be soliciting a broad range of ideas and not limiting yourself to official 5e mechanics. Unfortunately, idea-generation questions are a poor fit for RPG.SE, as they're primarily opinion-based with no way to choose a single "best" answer, and might be better suited to a forum or Role-playing Games Chat. If you limit your scope to existing mechanics, and narrow your question so it's not too broad/a duplicate, it may be answerable here. \$\endgroup\$
    – V2Blast
    Commented Sep 5, 2020 at 3:46

2 Answers 2


Ethereal Guardians.

Your first concern about ethereal intruders could best be handled by guardians who were themselves ethereal. These could be monsters of some kind, if your setting has such creatures, or they could be a squad of Airman Snuffy's with M-16s and cloaks of etherealness.

Limit Personnel to Prevent Scrying.

Scrying becomes harder when the caster does not know the subject of the scrying. To better secure against the spell, you would want your facility personnel to all be people who have never met a foreign or enemy spell caster. You would want to keep your top military commanders from interacting with potential foreign spell casters and getting to know them. You would also want to rotate people through fairly regularly and sequester them from the public while they are stationed there, so potential scryers would have trouble knowing who was even there. It would require a significant level of effort and would not be foolproof.

Control objects leaving the facility.

The best chance for an accurate teleportation into the facility would be for the spell caster to get an object that had been there in the last six months. So, nothing leaves. The crew arrives, goes to a secured building that is within the perimeter, but outside the sensitive area, to change clothes. They wear their work uniforms (every single garment plus shoes) in for work, and then leave everything in the secure changing room and wear their other clothes out--the clothes that spent the day in the secure room but outside the sensitive area. Without a permanent circle or associated object, the odds of successful transportation drop. You would then change the inside of the facility periodically to throw off any potential enemies who may have gained familiarity or at least seen casually while there.

None of this is fool proof, but these are some ways to combat these issues.


Mordenkainen's Private Sanctum

Within your lair, you want to

  • Block ethereal travel.

  • Block divination magic.

  • Block teleportation.

The private sanctum spell (from fifth edition) can do all this and more within the warded area, with one hundred percent reliability. It wards a cube up to 100 feet on a side, or more if you use a higher level spell slot. You can use multiple castings of the spell to cover a larger area. It is a 4th level spell, so it is available to mid-level casters.

Its duration is 24 hours, but if you cast this spell in the same spot every day it becomes permanent. Casting this spell daily would be part of the construction of the lair.


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