Sources of Damage Reduction available to players

[Staffan]

Magic item: Armor of Invulnerability (DR 5/magic).

Complete Warrior has a series of armor abilities that give DR 5/(two damage types), e.g. axeblock gives DR 5/bludgeoning or piercing (I think the other two are hammerblock and spearblock). If you combine the abilities, you remove one of the penetrating damage types (e.g. axeblock and hammerblock would be DR 5/piercing).

Warforged with the Adamantine Body feat gets DR 2/adamantine, and I think there's a feat that increases it.

Inertial barrier is the psionic equivalent of stoneskin, but gives 5/- instead of 15/adamantine.

That's what I can think of off-hand that hasn't already been mentioned.

 

[Rkhet]

Assume Supernatural Ability from SS plus Polymorph can be used to gain DR.

Note that Polymorph doesn't normally get you DR, since that's an ability, not an attack. Shapechange does, though.