What is the limit to a Glyph of Warding's trigger?

Question

So, say you are a wizard 15/warlock 2. You have the Lance of Lethargy invocation, which pushes an enemy you target with eldritch blast and hit back 10 feet. Say you put a demiplane entrance ~5 feet behind the enemy you target with it. When you hit, you throw the enemy in. Before all this, you had put a Glyph of Warding in there on one of the surfaces. What would be the limit to the trigger for this? Would it be forced to be touch or proximity, or could you base it off something like hostility towards the caster?

... When you cast this spell, you inscribe a glyph that later unleashes a magical effect ... You decide what triggers the glyph when you cast the spell. For glyphs inscribed on a surface, the most typical triggers include touching or standing on the glyph, ... (PHB 245)

The key word here is "typical". Based on Google's definition, the informal definition of "typical" is

showing the characteristics expected of or popularly associated with a particular person, situation, or thing.

This means, if my assumption is true, that the triggers in the PHB are only the most common ones. Other than the one about being forcibly at maximum 10 feet in diameter in the PHB, I cannot see a limit. Though I probably should assume this would all be DM discretion, (and I know that I sound like a broken record here) but could the trigger be hostility toward the caster, or something else, like being a specific race, gender, from a specific place, etc., or would it be forced to being something from the PHB?

Answer 1

Any additional triggering conditions are completely up to the DM

The only limits to the spell are what is written in the spell itself, so let's look at what the spell says:

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

and then goes on to list some things that can be used to trigger can definitely detect giving "typical" examples of triggers. However, the text doesn't in any way imply that the list is exhaustive. The spell lists as examples of possible things that the trigger can detect:

• physical contact with the glyph
• if the glyph is covered/uncovered
• proximity of creatures
• status of the object on which it is inscribed
• if it can be seen or not and if it is being/has been read

Note that all of these triggers seem to hinge on a direct relation to the area around the physical glyph or manipulating the glyph itself (though it's not clear if that is an intentional restriction or just a coincidence in the examples they chose).

The listing of trigger refinements is less clear on whether it is exhaustive or just listing examples however:

• "circumstances" surrounding the trigger
• physical characteristics
• creature kind
• alignment

Specifically, the "circumstances" option seems to have pretty much unlimited power when interpreted broadly.

DM ruling is needed

In 5e, any kind of ambiguity or unclarity of a spell and any additional effects beyond what is written in a spell is up to the DM to clarify. Thus, any other triggers that aren't listed as examples (or very similar to them) would need to be ruled on specifically by your DM with little help from the rules (for better or worse).

If you are a DM in a position where you are trying to decide on the limits of the triggers I recommend reading several other Q&As here where specific aspects of it are discussed:

• Can your own death be a trigger for Glyph of Warding?
• Is there a limit on the "detection range" of Glyph of Warding's trigger?
• Can the Glyph of Warding spell detect whether a creature passed or failed a saving throw?
• Does a Spell Glyph need to "see" the target to activate?

Your specific example of hostility

Basing a trigger refinement off of hostility towards the caster seems to me personally to be a bit of a tough sell in general. This would, at times, require the glyph to essentially read the mind or intentions of a creature which would be a very powerful ability to grant it, possibly even trodding on the toes of other spells and abilities in a bad way. If I were DMing this and you asked me about it, I would recommend the trigger be rephrased to say "take hostile action against the caster" because at least that is observable. That would seem to fit into the nebulous category of "circumstances" by my reading at least. Another DM might disagree with either of these interpretations, but I think this is a reasonable ruling.