Does a Glyph of Warding have its own agency or a limited omniscience in the game?

The case of the nasty Drow, invisible evil Sprite and the blue Orc.

Some specifications for the trigger of a Glyph of Warding are more obvious than others. For instance, I am a Dwarf Cleric and set a Glyph of Warding (Explosive Runes) underground to be triggered by the next Drow that walks past my favourite stalagmite. It is simple: I can see under ground because of my Darkvision; I know what a Drow is. Therefore the Glyph of Warding's trigger is something that I could potentially see and/or know.

Now, what happens when I set the trigger to be an invisible evil Sprite? I can't normally see these creatures. So, in this case does the Glyph of Warding still trigger when an "invisible evil Sprite" passes by and "Kaboom! Bye-bye evil Sprite!". Also, how can it know that Sprite is evil, when I don't even know that?

Then there is this situation: I am a completely colour-blind and my mission is to capture the blue Orc without breaking my cover, by say asking every punter a stupid question like: "Have you seen a blue Orc around these parts, me matey?!" So, I come up with a plan. I use a Glyph of Warding on a bridge which most of the village use on a regular basis. The trigger is: when a blue orc walks over the slab of stone, cast Light. I lie in waiting, watching out for my Light cantrip to trigger. Once I spot the blue Orc, I will follow her/him and plan the capture.

So Orc-ward...!

There is a deeper question at the heart of my question in that Glyph of Warding appears to have its own sense of agency in the game. The magic cast, that recognises the specific conditions for a trigger, appears to be observant and have possibly a omniscience limited to its immediate surroudings.

So, does a Glyph of Warding have its own agency or a limited omniscience in the game?

Glyph of Warding

You decide what triggers the glyph when you cast the spell. [...]

You can further refine the trigger so the spell activates only under certain circumstances or according to physical characteristics (such as height or weight), creature kind (for example, the ward could be set to affect aberrations or drow), or alignment. You can also set conditions for creatures that don’t trigger the glyph, such as those who say a certain password.

When you inscribe the glyph, choose explosive runes or a spell glyph.


2 Answers 2


The inscribed glyph is magic.

Your character's corporeal capabilities are more limited than those which he draws upon by manipulating the subtle weave of magic inherent to the cosmos.

Wizards are not taught to imbue the glyph of warding with agency, it is not a sentient inscription.

You specify a trigger that may activate the ward. The trigger can include the approach of a creature with a chosen alignment; such as the "evil sprite" in your example.

Your character may not be able to sense the alignment of another creature, or it's other features, but your powerful use of magic will guide the inscription to activate when the appropriate conditions are met. The magic of the multiverse will make it so.

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    \$\begingroup\$ Yup. Because magic. +1. \$\endgroup\$
    – NotArch
    Commented Feb 5, 2020 at 2:16
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    \$\begingroup\$ I can't help but think that this is a slippery slope. What if the trigger were "when a creature that intends me harm enters this square"? Or "when a creature that has kicked a puppy at least once in its life crosses this line"? What's to stop it from being an infallible engine for detecting lies, criminals, or shapeshifters, etc? This is arguably a correct raw interpretation, but I think it is dangerous to apply without house rules - i.e. the spell is likely broken out of the box. \$\endgroup\$
    – cpcodes
    Commented Feb 5, 2020 at 18:19
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    \$\begingroup\$ @cpcodes DM adjudication on a trigger is not a house rule. \$\endgroup\$
    – NotArch
    Commented Feb 5, 2020 at 21:50
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    \$\begingroup\$ @Upper_Case Magic is capable of solving a lot of problems, but one of the things it generally can't do is make decisions for you, and it's essential that it can't, because making decisions is the way players participate in the game. This is exactly the issue with Glyph of Warding: it's perilously close to being better at making decisions than the player can be. \$\endgroup\$
    – Mark Wells
    Commented Feb 6, 2020 at 1:19
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    \$\begingroup\$ "light if this creature is going to return safe and successfully from the quest to kill the evil sorcerer" ... then only attempt the quest if it triggers a light for yourself... \$\endgroup\$
    – Cœur
    Commented Feb 6, 2020 at 8:07

The rules do not say

The rules do not specify whether the glyph spell does or does not possess agency. It is possible to create perfectly sensible implementations of the rules that don't give the glyph agency. It is also possible to create perfectly sensible settings where the glyph does have agency. The rules expect to be adapted into a wide variety of setting implementations and this omission, like many, exist therefor, so that the content they are attached to can be used without major modification in a wide variety of campaigns.

Detecting stuff you can't otherwise detect in no way implies agency

Your examples of agency seem to have nothing to do with the concept. An agent is an entity that makes choices. Your examples have to do with 'knowing' stuff you don't know, where knowing means differentiating on the basis of. That's not a very unusual trait-- you would have a hard time judging the volume of a metal sphere but if you put it in a partially-water-filled graduated cylinder the cylinder can tell you how much volume it had. That's not evidence that the cylinder is alive, it's evidence that the cylinder is a measuring device. Your examples, likewise, show that the glyph is a potent measuring device, but there's no reason to suspect cognitive abilities of any kind on that basis.


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