# Forum > Gaming > Roleplaying Games > D&D 5e/Next >  Architecture with Forbiddance

## No brains

Owing to the fact that I have no brains (hence the name), I am puzzling out how to design dungeon floor plans that can use Forbiddance effectively.

What are some floor plans, expressed in 5x5 squares*, that can make use of the 40,000 square feet of Forbiddance? I think it gives me around 16000 5x5 squares, but what are some shapes I can make with that? Great big squares? An ice cube tray of rooms? A spiral hall leading to a central room? Does anyone with proficiency in mathematics have any good suggestions for weird buildings we can make?

*It's locked to 30 feet vertically.

*Spoiler: Bonus question for people who help with the first bit*
Show

Say if a Babau, a Glabrezu, or any other creature that could just spam Dispel Magic comes up against the edge of Forbiddance, how would you rule its attempts to dispel forbiddance to work? Does a successful dispel undo the protection of all areas under that spell? Can they dispel from the edge or do they need to see the center of mass/ point of origin of the spell? These are more ideas for making the most use out of Forbiddance as a dungeon feature.

----------


## Lord Torath

> Owing to the fact that I have no brains (hence the name), I am puzzling out how to design dungeon floor plans that can use Forbiddance effectively.
> 
> What are some floor plans, expressed in 5x5 squares*, that can make use of the 40,000 square feet of Forbiddance? I think it gives me around 16000 5x5 squares, but what are some shapes I can make with that? Great big squares? An ice cube tray of rooms? A spiral hall leading to a central room? Does anyone with proficiency in mathematics have any good suggestions for weird buildings we can make?
> 
> *It's locked to 30 feet vertically.
> 
> *Spoiler: Bonus question for people who help with the first bit*
> Show
> 
> Say if a Babau, a Glabrezu, or any other creature that could just spam Dispel Magic comes up against the edge of Forbiddance, how would you rule its attempts to dispel forbiddance to work? Does a successful dispel undo the protection of all areas under that spell? Can they dispel from the edge or do they need to see the center of mass/ point of origin of the spell? These are more ideas for making the most use out of Forbiddance as a dungeon feature.


Just to be Properly PedanticTM, your math is off by an order of magnitude.  40,000/25 = 1,600 five-foot squares.

That'll make one large square 40 squares (200 feet) on a side.

----------


## Sigreid

First, you don't really have to cover the whole dungeon or building or whatever.  Really, you just need to cover the paths in.

Second, afb, but I believe dispell magic cancels the whole spell.  So, you're better off with multiple smaller castings.

----------


## strangebloke

> First, you don't really have to cover the whole dungeon or building or whatever.  Really, you just need to cover the paths in.
> 
> Second, afb, but I believe dispell magic cancels the whole spell.  So, you're better off with multiple smaller castings.


I mean, the question of what you're trying to accomplish is the most important one here.

Generally I think of forbiddance as good for dealing with planeshifters and shapeshifters. For planeshifters, you need to cover the whole area you're protecting. For handling succubi and such coming in the front door, you only need to cast on the front door.

So a 40x40x30 cube, or a massive area of hallways and doors. The true wizard pro strat is to put the entire cube in a space that's basically inaccessible, like deep underground, and have a single 10x10 teleport landing zone that's the only point of access, with everything else covered by forbiddance.

Either way, IMO dispel magic isn't the most important thing to worry about.. You can't teleport into the space regardless, you _have_ to teleport outside the area and walk in. The niche case where a devil is assaulting the building and trying to dispel your forbiddance before walking in is something that can happen, but overall feels pretty rare. And either way at that point forbiddance has done its job of slowing the enemy down.

----------


## Segev

Interesting side note: the expensive material component is powdered ruby, but it is not consumed when you cast the spell (unless you do it thirty days in a row to make it permanent). this means you can sweep up the powdered ruby used in the ritual to recover it, theoretically. Or that you don't have to do anything with it that makes its powdered form physically useful to the ritual. 

Just an interesting bit, to me.

----------


## No brains

> Just to be Properly PedanticTM, your math is off by an order of magnitude.  40,000/25 = 1,600 five-foot squares.
> 
> That'll make one large square 40 squares (200 feet) on a side.


Thank you for being the Billy Mays of pedantry. That extra zero is a hybrid of a complicated lineage of typo, an 'is that right?' and trollbait to catch attention. That's the beautiful thing about math errors, you can express so much confusing information with even just a 0.

The curious thing about divvying up that big 200 foot square is what other common D&D stuff can fit in that area? I suppose you could forbid one room that is too big to firebolt, makes use of the range of longbows and eldritch lances, and can take too long for even a rogue to cross in one turn.

What I want to play with is what other interesting shapes I can make out of 40,000 square feet expressed as 5-foot squares. I guess I can make a 600 foot hall that is 65 feet wide that has some sharpshooting longbowmen at the other end, give the PCs a few rounds of having to run straight at their attackers. Maybe I could make a 480 foot long series of 80 foot square rooms that are targeted by fireballs that only leave the corners safe. Maybe stuff with zig-zags or spirals? What can I do with all those squares? I wish I had some legos handy.




> First, you don't really have to cover the whole dungeon or building or whatever.  Really, you just need to cover the paths in.
> 
> Second, afb, but I believe dispell magic cancels the whole spell.  So, you're better off with multiple smaller castings.


I don't think I want to skimp on a barrier that prevents teleportation into a building. When you use more than 3D space, everywhere is 'the way in'. While many teleport effects are line of sight, some good ones aren't. Ethereal creatures can even take the time to scout 'landing zones' and figure out where they would be able to port in.

As for 'smaller' castings, that's one of the things that has me interested in interesting geometric architecture. Using doors, turns, and other spatial tricks, it's possible to make every 40,000 feet its own point of failure that won't compromise adjoining rooms.




> I mean, the question of what you're trying to accomplish is the most important one here.
> 
> Generally I think of forbiddance as good for dealing with planeshifters and shapeshifters. For planeshifters, you need to cover the whole area you're protecting. For handling succubi and such coming in the front door, you only need to cast on the front door.
> 
> So a 40x40x30 cube, or a massive area of hallways and doors. The true wizard pro strat is to put the entire cube in a space that's basically inaccessible, like deep underground, and have a single 10x10 teleport landing zone that's the only point of access, with everything else covered by forbiddance.
> 
> Either way, IMO dispel magic isn't the most important thing to worry about.. You can't teleport into the space regardless, you _have_ to teleport outside the area and walk in. The niche case where a devil is assaulting the building and trying to dispel your forbiddance before walking in is something that can happen, but overall feels pretty rare. And either way at that point forbiddance has done its job of slowing the enemy down.


I think you have a good point about Forbiddance being another tool for slowing an invasion rather than stopping one. Ideally, you would want to pair this with defenses that can kill a Babau or Glabrezu faster than it can tear down the defense. Which is another good reason to be clever with the shape of that landing zone- what is the most stacked defense you can fit into an area that is also usefully warded? 

Though this got me thinking about one real trick: if you leave a gap in Forbiddance that's only big enough for a tiny creature, you'll never have to worry about a large Glabrezu besieging your enchantment. Medium Babau and Ultroloths that use determinations, Enlarge/Reduce, and Squeezing rules, still get a minute to work.




> Interesting side note: the expensive material component is powdered ruby, but it is not consumed when you cast the spell (unless you do it thirty days in a row to make it permanent). this means you can sweep up the powdered ruby used in the ritual to recover it, theoretically. Or that you don't have to do anything with it that makes its powdered form physically useful to the ritual. 
> 
> Just an interesting bit, to me.


Are you postulating that it may be better to never actually enage the permanent version of the spell? That's an interesting theory, but few things that can cast high-level spells want to cast them every day in perpetuity. They may want to pay the 1000gp just for a vacation.

Or do you just think it's amusing to imagine a wizard hurriedly sweeping up their ruby powder to maske sure they save all of it after dusting it over an entire mansion?

Though it's possible to parse the material component as being any mix of holy water, incense, and ruby totaling 1000gp. That means in a pinch, you can drop 6 ruby molecules, burn just a whiff of incense, and kick over a Scrying focus full of 5 gallons of holy water (another magical math project I went into once.)

----------


## Segev

> Or do you just think it's amusing to imagine a wizard hurriedly sweeping up their ruby powder to maske sure they save all of it after dusting it over an entire mansion?


This one. It just amuses me. 

Technically, the spell doesn't describe how you use the powdered ruby, so it's quite possible you don't scatter it anywhere, but I definitely picture it as being sprinkled around the borders of the space during the casting time. I imagine an intended-to-be-permanent one would leave the components sprinkled about, or even work them into the architecture when it is built. But if it's a one-off - like, say, _forbiddance_ing your camp site - you would need to reclaim the powder and stuff. Which is amusing to picture.

----------


## Sigreid

> First, you don't really have to cover the whole dungeon or building or whatever.  Really, you just need to cover the paths in.
> 
> Second, afb, but I believe dispell magic cancels the whole spell.  So, you're better off with multiple smaller castings.


Ah, I was AFB and thinking of that spell that makes people avoid an area.

----------


## No brains

> Ah, I was AFB and thinking of that spell that makes people avoid an area.


I should probably check out Antipathy/ Sympathy too. I may be sleeping on that one. Forbiddance, Hallow, Guards and Wards are good ones though if anyone else wants to design a dungeon.

----------


## Samayu

> ...But if it's a one-off - like, say, _forbiddance_ing your camp site - you would need to reclaim the powder and stuff. Which is amusing to picture.


Why are you carrying a bushel of dirt, leaves and twigs?
Spell component.
What spell requires dirt?
Um... Forbiddance.
I thought that was ruby dust.
There's ruby dust mixed in. 
Not very pure ruby now, is it? 
It just requires ruby dust on the ground.
OK, but I hope we never have to rely on it!

----------


## No brains

If it were up to you, as either a player or a DM, would you prefer to ward an area with Forbiddance or Modenkainen's Private Sanctum? Both keep creatures from teleporting in, but Sanctum keeps them from teleporting out too. Forbiddance seems to affect a much larger area though. Sanctum has no component, but Forbiddance can be cast as a ritual. 

IIRC, doesn't Mighty Fortress, Druid Grove, and Temple of the Gods have similar effects? I'll need to edit in more info.

----------


## Sigreid

> If it were up to you, as either a player or a DM, would you prefer to ward an area with Forbiddance or Modenkainen's Private Sanctum? Both keep creatures from teleporting in, but Sanctum keeps them from teleporting out too. Forbiddance seems to affect a much larger area though. Sanctum has no component, but Forbiddance can be cast as a ritual. 
> 
> IIRC, doesn't Mighty Fortress, Druid Grove, and Temple of the Gods have similar effects? I'll need to edit in more info.


If I'm playing a character with access to Private Sanctum, that spell cast to permanency.  From there I'd look to see if Forbiddance gives any additional perks.  Also, if one of my buddies can Hallow the ground, I'm doing that too.

----------

