DR of 10 / Evil mean I have DR 10 only vs evil creatures or DR 10 vs all but evil weapons?

[Grayfeather]

DM seems to think its DR only against evil creatures. I think its 10 vs everything other than evil aligned weapons or +3 and above. Please clarify.

[Michael Sayre]

It means evil weapons will bypass your DR. It takes a +5 weapon to bypass alignment-based DR, so if you have DR 10/Evil, someone will need to hit you with an evil aligned attack or a +5 weapon, otherwise you'll ignore the first 10 points of damage.

[Grayfeather]

Ssalarn wrote:

It means evil weapons will bypass your DR. It takes a +5 weapon to bypass alignment-based DR, so if you have DR 10/Evil, someone will need to hit you with an evil aligned attack or a +5 weapon, otherwise you'll ignore the first 10 points of damage.

Sweet, thanks.

[Bill Dunn]

The entry after the slash is what penetrates the DR. That means it takes an unholy weapon, other evil aligned weapon, or other attack from a creature whose weapons count as evil for penetrating DR (it will say so in their stat block) to avoid that 10 points of DR.

Note that it takes a +5 weapon to penetrate alignment-based DR if the weapon is not aligned. Not +3.

Edit: Dang. Ninjas beat me to it.

[The_Hanged_Man]

Also, creatures of the evil subtype (not alignment) overcome the DR. The subtype is in parenthesis after the monster type, e.g. Outsider (evil).

[Sean K Reynolds]

The rules have the answer:

Core Rulebook glossary entry on Damage Reduction:
Damage Reduction
Some magic creatures have the supernatural ability to instantly heal damage from weapons or ignore blows altogether as though they were invulnerable.
The numerical part of a creature's damage reduction (or DR) is the amount of damage the creature ignores from normal attacks. Usually, a certain type of weapon can overcome this reduction (see Overcoming DR). This information is separated from the damage reduction number by a slash. For example, DR 5/magic means that a creature takes 5 less points of damage from all weapons that are not magic. If a dash follows the slash, then the damage reduction is effective against any attack that does not ignore damage reduction.