What does DR look like?

[Saeviomagy]

In the Core Rules, hit point damage is not necessarily actual physical damage to the creature's body. Hit points are an abstract covering a lot of different things, many of them not visible. So, there doesn't need to be a visible effect when DR is encountered.

I swing
You miss

I swing
You miss

I swing
You miss

I swing
You miss

I swing
You miss

I swing
The monster drops dead.

Doesn't quite have the makings of a great battle, does it?

 

[Umbran]

I swing
You miss

There are as many ways to describe misses and near misses are there ways to describe visible damage to flesh.

What needs to be gotten across to the player is that the attempt had an effect upon the creature. It needed to really try to get out of the way, burn up some of it's energy, luck, karma. It needed to stretch so far it pulled muscles, twisted an ankle a bit. It winces in pain, or growls in mixed fear and anger....

Great battles end in spilling blood. But typcially, not much blood actually gets spilled before the end. Just a trickle at the corner of the mouth, some bruises, a bit of a limp, and a lot of sweat.

 

[schnee]

So, there doesn't need to be a visible effect when DR is encountered.

The DM's guide specifically says the effect should be obvious.

I agree with that, as DR is enough to change the CR and possibly dictate a change in tactics. It's the same as a vulnerability to a certain effect... if Trolls don't exhibit some obvious cringing/reaction to fire, how would characters ever really figure out to use it?

 

[Doomhawk]

When I think about DR, one of the things that comes to mind is an episode of Samurai Jack wherein Jack has to fight some Egyptian demon-jackal-monsters. He strikes one of them, and cuts a huge gash through it, which flaps around... and then instantly closes. It looks better since it's a cartoon and they don't have to worry about anatomy details, but still, I've always liked that method.

Characters might figure out that trolls are vulnerable to fire when the only adventurers who come back alive from the Troll Swamps are the pyromaniacs...