Do Damage reductions stack or Overlap?

[Sims]

Spell resistance overlap, I remember seeing that. But say I have a DR of 10/- and then I find a Ring that gives me DR 15/Adamantine.

If I equip it, will my new DR be a 25? Or just the higher of the two?

[The Rose Dragon]

If you are attacked by a non-adamantine weapon, your DR is 15. If you are attacked by an adamantine weapon, your DR is 10.

[Alleran]

You use the best one that applies for the situation. You don't stack them.

[Tyger]

The rules for this are on the SRD (http://www.d20srd.org/srd/specialAbilities.htm#damageReduction) if you want to really dig into them.

EDIT: Its worth noting, should your group be using the Armor as DR rules from the UA, that those armor DRs do stack... we missed it, thought we houseruled it to work that way, then discovered we'd been following the rules all along.

[Cog]

Yeah, DR/- often stacks with other DR/-. You can't assume it, since the general rule would still take precedence, but a lot of the sources for /- have that clause, usually with an eye toward benefiting Barbarians.

[Sacrieur]

Yeah, DR/- often stacks with other DR/-. You can't assume it, since the general rule would still take precedence, but a lot of the sources for /- have that clause, usually with an eye toward benefiting Barbarians.

What?

"If a creature has damage reduction from more than one source, the two forms of damage reduction do not stack. Instead, the creature gets the benefit of the best damage reduction in a given situation."

[The Cat Goddess]

Personally, there are some kinds of DR that I would allow to always stack...

Like Barbarian & Warlock class DR.

Other types should overlap...

If a Werewolf (DR 10/Silver) wears a Shirt of Angels (DR 10/Good), then you would need a Good-Aligned, Silver weapon to penetrate his 10 DR.

[Tyger]

Yeah, DR/- often stacks with other DR/-. You can't assume it, since the general rule would still take precedence, but a lot of the sources for /- have that clause, usually with an eye toward benefiting Barbarians.

Actually, if you aren't using the UA system, almost no DR stacks, save a very few which specifically state that they do.

[MammonAzrael]

Actually, if you aren't using the UA system, almost no DR stacks, save a very few which specifically state that they do.

And most of those are from feats and such that are specifically intended to improve existing DR.

And while I love the flavor of Roll With It, sadly a 2 point boost is just not worth a feat.

[KillianHawkeye]

Other types should overlap...

If a Werewolf (DR 10/Silver) wears a Shirt of Angels (DR 10/Good), then you would need a Good-Aligned, Silver weapon to penetrate his 10 DR.

That is exactly how it DOES work, because you need an attack that bypasses both forms of DR.

[Cog]

Hm. I could have sworn I've seen a few Barb-themed prestige classes that progressed DR, but looking through the Completes I can't find any, so I suspect they're rare elsewhere too. Retracted!