Are there any sources more concretely describing the Shield spell?

Question

This question stems from an exercise in rule interpretation that happened in a friendly brawl after our game ended. A Dragonborn blasted an acid breath at a mage player who blurted out "I use the shield spell." Now, we figured it didn't really matter since the dragon breath is a guaranteed hit (although half damage on the saving throw), but it raised the question of "what is the shield spell?"

I was wondering how I should explain what it is to my players, as in from a narrative perspective. Obviously it isn't an impenetrable force field, because it only raises AC +5. But what is it? If an arrow hits the mage and he decides to block it with shield, how does he do that? "An invisible barrier of magic force" that allows some arrows, acid splashes, and swords through, but not all of them?

New to the non-video game RPG and wondered if someone could shed light on DM-ing the Shield spell. I want to know how other people fluff it up. We like realism, but also just good fluffy magic narration. A good answer would tell me some great ways to visualize the shield spell that would also help it make sense.

Does anyone know of a written reference or depicted shield spell that would give an idea of how the spell manifests?

Answer 1

From the description of the Shield spell:

An invisible barrier of magical force appears and protects you.

As you say, it doesn't block everything, so it can't be a perfect force field. You have a few options for description, though, since the rules don't give you any more than this.

1. The way most people seem to think of Shield is that it is an impenetrable barrier, but it is the size and shape of a shield. So it blocks everything that hits it, but it's not a perfect defense. For a great example of this, see this OotS strip.
2. Alternatively, it's a barrier of force, meaning that it pushes away anything that comes near it, but a strong enough attack pushes through and hits its target anyway.
3. Oddly enough, both of these could be true. If it is a barrier that is difficult but not impossible to penetrate, and limited in size, it would certainly explain why things keep hitting the person protected by it.
4. And finally, as always in D&D, it's up to you and your player(s). Fluff is the most malleable part of the system. If a player decided that they wanted their Shield spell to be an invisible guardian that hovers by them and snatches arrows out of the air (or whatever), as long as you're ok with it, the system is ok with it. How Shield works doesn't matter, all the rules care about are the effect.