Castle Defenses and Glyphs of Warding

[The Deej]

So, the 5E group I'm in has been recently granted a fiefdom, and we've began constructing a castle. We have the typical mundane defenses established (walls, gatehouse, moat), plus a Hallow spell cast on the area of the gatehouse (courage secondary effect). The at-large threats in the world currently are an undead plague, and a Cyclops that is trying to gather an army of giants, gnolls, and goblins. My character is a UA ranger, Darkstalker conclave, and I'll be getting Glyph of Warding come level 9. I'm wondering what fun things I can put into a spell glyph version of it for some extra castle defenses. some of the things I've already though of are as follows:


fireball
plant growth
conjure animals (sharks in the moat)


also, according to how it's worded, it looks like one could intentionally set them to target friendlies as well, and put multiple concentration buffs on them


haste
enlarge
bless
shield of faith
etc

[Waterdeep Merch]

You could dig hollows around the castle, supported by a lattice of beams that are easily destroyed by the Shatter spell. Fill these hollows with spikes, or if you have the time and money, hunting traps and caltrops.

You could do the same thing with any bridges over the moat, to dump a bunch of soldiers in. Be sure to stock it with something vicious if you can.

If you'd rather not make the landscape hard for you to travel afterwards, make more stable tunnels, then load them with fats, lumber, and oil, and a few 'breathing' tunnels that are near these glyphs. Have them cast Fireball, making sure it hits both the approaching army and starts setting the tunnels on fire. It'll turn the battlefield into a stovetop and generate a smokescreen for your castle. Make sure the tunnels aren't too close to you, both to avoid the heat and to keep the smoke from negatively affecting your own archers while they pick things off the walls.

You can use obvious glyphs as a funnel. A few wooden slats set up with glyphs to explode, set up around places you'd rather not see an invading force. Some can even be dummies to save you money, just not any around the outer edges or nearer yourself. Don't put these slats around a particular focal point- this way, an army will naturally head to this location. If you're worried the enemy commander might realize this is an obvious trap, purposely destroy a bunch of these slats with fire and leave them around the spot you want them to go, to make it look like you haven't had a chance to replace them from a previous attack, and try to make this point look like an otherwise undefended side. Cluster catapults, trebuchets, ballistae, murder holes, boiling oil, and whatever other nasty surprises you can think of to defend this point. Hide them, and don't unleash until the enemy closes the distance. By the time you start firing on them, it should be too late to avoid.

Don't neglect illusion potential, either. The din of battle, yelling soldiers, even crying villagers might be useful if it comes from the right direction. The appearance of a group of footmen might give you the moment you need to stop an advance. Password lock these, maybe require a certain horn call to activate. Actually, I recommend that for most of your traps. Remote activation is going to be better than automatic activation under most circumstances.

Some grease spells near the top of your walls might do wonders. Web as well near the base, if you can prepare some fire to go with it. Obvious ladders and scaffolding that blast themselves apart might catch a gullible group of soldiers off guard.

Can someone do Alarms? You should have Alarms. You don't really need glyphs for those, but someone should set these up. Even if you're caught in a surprise attack, have a caster go around and set alarms all over the perimeter. If you get breeched, you need to know. Let the signal be mental, so that you have a chance to catch the invaders off guard. Your enemy should never know your plan; they should believe that everything they're doing is working flawlessly. Cocky opponents make stupid mistakes, and are easy to trick.

[Sigreid]

Cloud kill comes to mind.

[Kadesh]

Illusions programmed to cover actual defenses, and show false weakpoints/defended locations.

[The Deej]

Cloud kill comes to mind.

The catch there is that Cloudkill is 5th level. A spell glyph can't have a spell in it that's a higher level than what Glyph of Warding cast at, so I'm not going to be able to get anything higher than a 3rd in one for...a very long time. And I might never wind up being able to do higher than a 4th.

[Sigreid]

The catch there is that Cloudkill is 5th level. A spell glyph can't have a spell in it that's a higher level than what Glyph of Warding cast at, so I'm not going to be able to get anything higher than a 3rd in one for...a very long time. And I might never wind up being able to do higher than a 4th.

Not looking at the book, but what about stinking cloud then?

[JackPhoenix]

While Glyph of Warding is awesome for defensive purposes, be careful with the trigger. You don't want all your preparation go off when random bird lands on the wrong spot, or when foreign diplomat with bodyguards comes to visit.

[SLOTHRPG95]

Make your Glyphs of Warding big, and bad, and obvious. They should be nasty, but not hidden, in order to (as previously mentioned) funnel the enemy into a kill zone. Treat them like landmines. They're area denial tools, and rely just as much on psychological factor of the enemy knowing they're there and nasty and then deciding "oh well might as well charge through the center where all the bows are pointed" as they do on actual damage-dealing potential. I mean, sure make it punishing if they're set off so nobody decides "eh I'll chance the Glyph field instead" but you don't actually want them going off. Then they become useless, and need to be replaced.

[elfinboy]

Place animate dead glyphs all over the field so every time you kill an enemy you get a zombie fighting for you

also place them on the walls so enemies scaling the walls get turned into skeletons so they can snipe the leaders

[JackPhoenix]

Animate Dead doesn't target a single creature or an area, so it's not valid spell for Glyph of Warding.

Illusions don't really work. While they are valid spells, the glyph itself can't make the decisions required to make illusions work (i.e. what sort of illusion appears), and the original caster has no control over its form.

Remotely activated glyphs suggested by Waterdeep Merch don't work, because the glyph targets the creture that triggered it.

[Sigreid]

So, with the animate dead thing you could stock animated dead in a locked structure outside the walls if you can figure a way to open it from a distance. Since uncontrolled skeletons are described as viscous murder machines and oh look, people to be murdered.

[The Deej]

Make your Glyphs of Warding big, and bad, and obvious. They should be nasty, but not hidden, in order to (as previously mentioned) funnel the enemy into a kill zone. Treat them like landmines. They're area denial tools, and rely just as much on psychological factor of the enemy knowing they're there and nasty and then deciding "oh well might as well charge through the center where all the bows are pointed" as they do on actual damage-dealing potential. I mean, sure make it punishing if they're set off so nobody decides "eh I'll chance the Glyph field instead" but you don't actually want them going off. Then they become useless, and need to be replaced.

This could maybe be done, but artificial effort would have to be taken. The glyphs as written need a [spell DC] Investigation check to find, so they would have to be put on obvious objects that stick out quite a bit, and some of them will probably have to be triggered for the enemy forces to figure out "oh, crap. those are friggin land mines" (well, depending on intelligence, probably). There will already be natural funneling, though, due to the moat and the bridge. I can still use the idea, though. I'm thinking with poles that come up to just a few feet short of the surface of the moat, packing glyphs with, say, call lightning (need to check, but pretty sure it's legal). 10 minutes continuous shots of electricity damage to anything in the water. Ought to be a big enough "heck no" that they just take the bridge.


Not looking at the book, but what about stinking cloud then?

Yep, that'll fit. Probably a good choice for right in front of the gatehouse.

[Waterdeep Merch]

Remotely activated glyphs suggested by Waterdeep Merch don't work, because the glyph targets the creture that triggered it.
It's a two-step thing, utilizing the password feature as-written. You set the activation trigger like "When the sound of a horn making two long, one short, and then one long call resounds, the glyph becomes active or inactive. While active, the glyph triggers whenever any creature approaches it within 10 feet."

This way, you can raise and lower your magical defenses as necessary, in whole or in part. Though I did forget the 'centered on' thing, namely for illusions. Sound is still useful- screaming soldiers from behind, if that's your precise wording, can be useful. Visual, maybe not so much- they'd have to appear within 10 feet, really limiting their options for distraction.

EDIT: Speaking of password locking and landmines, setting a couple in your kill zone that are hidden at it's climax, perhaps on the bridge, that are hidden and aren't active until you unlock them, is a great way to gather and then blow up an army. Set up a couple layers of them with different passwords, and you can keep resetting and blowing up different groups of lemmings.

[MaxWilson]

While you're at it, you might as well put up at least one permanent illusion (Major Image VI, no components consumed) every day while you're working on the castle, and maybe an arbitrary number of Magic Mouths too (10gp of components each, reusable).

Heh, I just realized that Magic Mouth + Kenku is actually kind of cool and lets you create arbitrary re-usable sound effects for your castle.

[EvilAnagram]

Reverse Gravity is great because you can place spikes on the ceiling and the ground.

[JackPhoenix]

It's a two-step thing, utilizing the password feature as-written. You set the activation trigger like "When the sound of a horn making two long, one short, and then one long call resounds, the glyph becomes active or inactive. While active, the glyph triggers whenever any creature approaches it within 10 feet."

This way, you can raise and lower your magical defenses as necessary, in whole or in part. Though I did forget the 'centered on' thing, namely for illusions. Sound is still useful- screaming soldiers from behind, if that's your precise wording, can be useful. Visual, maybe not so much- they'd have to appear within 10 feet, really limiting their options for distraction.

EDIT: Speaking of password locking and landmines, setting a couple in your kill zone that are hidden at it's climax, perhaps on the bridge, that are hidden and aren't active until you unlock them, is a great way to gather and then blow up an army. Set up a couple layers of them with different passwords, and you can keep resetting and blowing up different groups of lemmings.

There's no such thing as active or inactive glyph. You can create a password, and the glyph will ignore the creature that spoke the password, even if it would otherwise trigger based on other characteristics. It will still go off for anyone else.

[Sigreid]

There's no such thing as active or inactive glyph. You can create a password, and the glyph will ignore the creature that spoke the password, even if it would otherwise trigger based on other characteristics. It will still go off for anyone else.

You could just paint areas to look like they might be glyphs.

[Waterdeep Merch]

There's no such thing as active or inactive glyph. You can create a password, and the glyph will ignore the creature that spoke the password, even if it would otherwise trigger based on other characteristics. It will still go off for anyone else.
Sure there is. How else would you interpret "You decide what triggers the glyph when you cast the spell", and "You can also set conditions for creatures that don't trigger the glyph". Everything else are examples of how glyph of warding is usually set up, not an exhaustive list of possibilities. The fact that passwords can even work proves that it can function on an auditory basis, and can be specific too. It also shows that the glyph can be set to not function under specified circumstances- in this case, before it hears certain notes. Or we could work it backwards just using the former declaration of triggers, and simply give the sound as the first necessary distinction of the trigger. Preferably with a time limit on a length of time between the sound and the second, final part of the trigger.

[Vogie]

Reverse Gravity is great because you can place spikes on the ceiling and the ground.

Actually you could JUST have spikes on the ceiling, and a Glyph of warding covered by a flammable tapestry. You need to activate, just set fire to the tapestry, and then as the invaders enter the room, someone inevitably sets off the trap (or you use a relay), and they all fall straight up onto the spikes

[MintyNinja]

I don't know how wealthy your party is, but every single casting will cost you 200 gp in incense and diamond dust. You should really consider the best bang for your buck, here.

[The Deej]

Sure there is. How else would you interpret "You decide what triggers the glyph when you cast the spell", and "You can also set conditions for creatures that don't trigger the glyph". Everything else are examples of how glyph of warding is usually set up, not an exhaustive list of possibilities. The fact that passwords can even work proves that it can function on an auditory basis, and can be specific too. It also shows that the glyph can be set to not function under specified circumstances- in this case, before it hears certain notes. Or we could work it backwards just using the former declaration of triggers, and simply give the sound as the first necessary distinction of the trigger. Preferably with a time limit on a length of time between the sound and the second, final part of the trigger.

Semantics and technicality there. Strictly speaking, a glyph is always active and awaiting proper conditions to 'go boom'. Just because there are specific conditions that prevent it from 'going boom' doesn't mean that it's inactive. It just means that invalid logical switches are currently registered, therefore, no boom. But, semantics and technicality.

Personally, I think I'd rather just word a proper 'IFF-based' trigger for places that actually need to be traveled by friendlies, as the previously described "remote triggers" are a step too complex to be reliable in a frantic situation. No password needed, just come on through if you're a friendly, get a world of hurt if you're not. Everything else will be a minefield triggered by "intelligent creatures/beings that aren't me" or something like that. Allows me to maintain them, while keeping everyone else out.

[The Deej]

I don't know how wealthy your party is, but every single casting will cost you 200 gp in incense and diamond dust. You should really consider the best bang for your buck, here.

I'm aware. This is largely brainstorming for the future, and possibly coming up with something to spend my (soon to be) functionally useless gold on. Right now, we have enough gold to put a Hallow effect on the entire bailey of our castle, plus the keep, plus the temple we're building inside the walls. I imagine by the time I hit level 9, we'll have enough gold to ward most of the perimeter with glyphs, should we so desire, and lack any other item needs.

I mean, we have a fiefdom of our own, plus a newly founded merchant company that will start generating money at some point. And we already don't know what to do with our excess cash, as our attunement slots are all full, save for maybe one or two.

EDIT: some additional relevant context - the nation we are in is very magic-unfriendly (excepting divine magic). Arcane casters are illegal unless sanctioned, same with magic item trade.

[EvilAnagram]

Actually you could JUST have spikes on the ceiling, and a Glyph of warding covered by a flammable tapestry. You need to activate, just set fire to the tapestry, and then as the invaders enter the room, someone inevitably sets off the trap (or you use a relay), and they all fall straight up onto the spikes

You should probably have glyphs among the ceiling spikes to add some explosive runes to the fun.