The feat Roll With It (Savage Species, p. 39) contains come text that is confusing1:
This applies in addition to any damage reduction you have from other sources.
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.
Could this be an oversight since Savage Species is 3.0? Especially since it contains:
You may take this feat multiple times.
But it doesn't contain what, in D&D 3.5, is usually also stated after that bit of text:
It's effects stack.
Would the damage reduction of 2/- stack with existing damage reduction of x/-, or is it an exclusive damage reduction of 2/- that applies at the same time to x/magic (for example)?
If one took this feat multiple times, would it's effects stack?
Hypothetical (but very plausible) situation
7th Level Mineral Warrior Barbarian has DR 1/- from being a barbarian and DR 8/adamantine for being a Mineral Warrior. He takes the feat Roll With It. Does that simply improve his DR 1/- into DR 3/-? Is it an exclusive 2/- that also applies at the same time to DR 8/adamantine?
7th Level Dwarf Barbarian wants to take Roll With It, and plans on taking it every time he gains a feat.
1After searching with "roll with it" [dnd-3e] & [dnd-3.5e] and not finding anything.