D&D 5E World building: The forbiddance spell in military application

With the mention of a "sprinkling of holy water", I'd have thought there'd be a similar consumption of the "powdered ruby". Is there any reason to think this wouldn't be the case?
Last paragraph.

"...If you cast forbiddance every day for 30 days in the same location, the spell lasts until it is dispelled, and the material components are consumed on the last casting."

The parenthetical with the material components also doesn't say consumed. Compare to Raise Dead:

"* - (a diamond worth at least 500 gp, which the spell consumes)"

A few other spells use a "sprinkling" of holy water but have no listed material cost. I believe a Jeremy Crawford tweet said a sprinkling is a trivial amount so small that it has no effective cost (i.e. how many drops are in a pint?) I think there's some bad math there but its magic god-water so who knows, maybe it evaporates and goes back in the bottle.

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greg kaye

Mold earth is the true soldier's friend. A neophyte caster can move earth like a 100hp excavator. This is 1500x faster than using a shovel, replacing more than a thousand man-hours of labor with under an hour of finger wiggling (somatic only).

True, but arguably the shovel might still be needed to provide the "loose earth" that the spell says it can "excavate" and "move". Dirt and stone are also mentioned but I certainly don't see that stone could be moved if it's not loose.


SO a 4th level arcane spell that can be made perm over a year, and a 6th level divine one that can be made perm after a month. The Arcane one is lower level, and smaller and skips the damage and password features.

Over all yeah, these two can be used to great effect. Is there a list of spell that over time become permanent until dispelled?

Let's see, a quick search for "permanent" under spells in DDB only adds a bit
  • Temple of the Gods. Creates a temple if you cast it every day for a year. Kind of tricky though because you have to designate who can open the front door.
  • Mighty Fortress. Not as powerful as some of the other spells, but who doesn't like a fortress just 'cuz? You even get invisible servants, how cool is that?
  • Glyph of Warding. Permanent until it's triggered and can cast any spell you want.
Then there are things like continual flame that I incorporate into the world. Having a perfectly safe light always available is something we take for granted. Now take that light and make it available anywhere any time, it would be pretty incredible. It may cost a lot to cast, but most households in my campaign world have one because they literally last forever. You can even go the route of Eberron with magitech, which I do a limited degree.

One question with these spells (forbiddance, hallow, sanctum) that you may want to think about is can they be dispelled if you cast dispel magic at any point that the spell affects? I've always said no, you have to cast it at the point of origin which will typically be well protected.

True, but arguably the shovel might still be needed to provide the "loose earth" that the spell says it can "excavate" and "move". Dirt and stone are also mentioned but I certainly don't see that stone could be moved if it's not loose.
What you describe is "disturbed earth".

The opposite of "loose earth" is "compacted earth". All unconstrained soil is loose soil. Anything not contained beneath a structure/rock will become loose soil naturally due to water through the soil, frost heave, thermal cycling, organic decay, insects, etc.

Jeremy Crawford confirms as "think dirt, not stone."
I am an engineer, to compact earth needs either years/centuries* of being under massive rocks/buildings, large amounts of traffic (i.e. a road) or what we do today, use mechanical devices to apply force every 6-24" lift of material (either vibrating plates or massive steel rollers with studs).

As I said above, even this will revert to loose soil eventually.

*Mexico City is build on an old lake. Over the last 200 years there has been 20-ish feet of compaction and it still isn't done, with estimates of full compaction happening at 65ft.


It’s great to block scrying, it will force enemy to use good old spy and traitor!
One thing that is sad about those spells is they are absolute. With tech you can have a bypass, a flaw or weakness that can make things move. magic should be like that. You place a warding spells and your enemy try to bypass it. Written rules make this a kind of static.


Patron Badass
Is there a list of spell that over time become permanent until dispelled?
Off the top of my head, Hallow is permanent immediately when its cast (though its probably the most expensive spell on the list and requires a full day of casting).

Guards and Wards is also a 6th-level spell that requires a casting of every day for a year to become permanent.

It isn't much of a "stay out" spell as much as its designed to make dungeon crawls a lot less straightforward.

If you're running a high-level dungeon crawl, you need to ask yourself why isn't the BBEG's place using Guards and Wards. Because its as obvious and worthy of a security measure that it would be more unbelievable to know that the spell exists and it isn't being used for the demon king's army.

Like, I want you to think about how even a high-level wizard is going to be very annoyed that every corridor fight is done practically blind for you and not the enemy. Or every door needs to be either unlocked with a +10 to its DC or uses Knock which will constantly draw attention.

And if they don't want to deal with these effects, they will need to waste quite a good bit of spellslots casting Dispel Magic for each effect separately.

I can't stress enough how this spell can humble high-level casters.

greg kaye

So spells for buffing an area, that can be applied within fortifications, include:
Tiny Hut (3rd)
Private Sanctum (4th+)
Hallow (5th)
Forbiddance (6th) and
Temple of the Gods (7th)
+ Magnificent Mansion (7th)

Fortification creation spells include:
Temple of the Gods (7th) and
Mighty Fortress (8th)

Other buffs, which might find applicability in more detailed/customized contexts include
Glyph of warding (3rd) and
Guards and Wards (6th) for which, arguably, multiple castings of dispel magic may be required to remove all the ...s and ...s effects and which may work with most security when there are fewer ~people that know the password.

Arguably, these last spells may better suit bunker and established fortress situations.

This leads me to wonder how D&D situations might differ between those of Montgomery-type military generals out in the field and Churchill-type, typically behind-lines generals who are able to retreat to established bunkers. In D&D terms this might relate to leaders that are leveled and leaders that aren't.

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