[RPG] What qualifies as a surface in Glyph of Warding


Can a player specify the surface of a small object as the surface affected by Glyph of Warding?

One of my players decided to create guns in the world (there are no guns present until now) by having bullets constructed and putting the glyph on the flat end with the trigger as "Be struck by metal". He was going to have it at the end of a metal barrel with the trigger causing a small hammer to strike the flat end (Glyph) of the bullet triggering it and the force propelling the bullet forward. (He has also convinced an exiled dwarf smith willing to work with the "bloody complicated contraption.")

I conceded that the explosion will be smaller, he still needs to take a saving throw to not drop the gun and that it will be difficult to construct, load and operate. However one of the players argued that it's not a surface but rather an object that is being glyphed, so moving the bullets with you would break the spell without triggering.

Best Answer

Normally I'd say that this kind of use is a stretch, but in this case I'd say it works, for one very critical reason: you, the DM, are on board with this.

In my own game I would rule against it: a glyph on a surface is measured in feet in the spell's description, and regardless of it being vague otherwise, I would feel quite within my responsibility as the arbiter of the game reality to say that something so complex that it's normally measured in feet could not in any way be reduced down to mere fractions of an inch. (At this point I would also point out to the player that if they're determined, they can just research a new spell that does what they want directly instead of trying to press an ill-suited spell into service.)

However, this is your game, not mine, and the same principle applies: you are responsible for arbiting the game reality. And in this case, you are clearly on board with the player's use of the spell. You even have supplied a cooperative NPC dwarf to get around the problems of engineering that took centuries to solve in our own history of firearms!

The only issue seems to be that you have one (or more?) other player who isn't so on board. In this case, since you are willing to grant the use of the spell, your problem is not the spell, it's mollifying the objecting player(s).

To do that, reassure them that the ruling is in the best interest of the game being fun, which is the ultimate goal of play. "The spell is vague on that point. It's obviously not casting it in an object, so the object rules don't seem to apply, just the surface ones. It's a very small surface, but I'm willing to allow it because it's vague enough that it isn't clearly improper, and because the result will be a lot of fun." Modify as appropriate, based on your judgement and your knowledge of your friends.

If that approach doesn't work, there is probably a fresh question to be asked regarding the social situation surrounding this.