Adamantium Damage Reduction / Barbarian Damage Reduction - Questions

[JaWriter]

There was a polight conversation between me and my DM a while back, and now that I've found a nice player base to also get ideas from we can see if I can get some additional clarification on everyones favorite mechanic: damage reduction.

Okay, armor made of adamantium and the barbarians damage reduction looks something like this:

x/-

Breastplates give 3/- full plate give 5/-, and the barbarians ragie stuff gives potentially: 1-5/- over the course of level progression.

I know these don't stack.  But what all does this damage protection apply to?  I've read through the MM on how Damage Reduction works and came up with a couble basic conclusions:

1) All physical damage, regardless of magical +x bonus (since it's un-typed).
2) Does not apply to Energy Damage (Fire, Cold, Shock, Acid, Sonic, Shadow, (un-)Holy, and Force)  This means magic missile overcomes the DR right?
3) May or may not apply to falling damage.  [Part of the debate]
5) Will not "stack" so a 7th level barbarian (DR 1/-) wearing adamantium breastplate (DR 3/-) is still only considered to have DR 3/-.

Damage reduction also Synergized with other DR.  As long as your DR doesn't have the "Or" descriptor you get DR untill all requirements are met.  I.E.  Damage reduction cold iron OR good means either works, but DR 5/cold iron , DR 5/Good, means you have to whack it with a Good Cold Iron wiffle bat.  DR of 5 only applies once if you hit it with a wood stick (neither requirment is met).



How would these items interact with items or abilities that give other 'common' DR?  Such as adamantium DR 3/- and something that gave DR 1/magic?  or 1/+4? or DR 5/Silver (lycanthrompes)  They synergize (not the same damage reduction), but how is that handled?  Or is it just superior and unless the DR is higher than the armor base, you gain no additional benifit?

aaaand, finally, DR stacks with Fast healing right?  DR is applied first then fast healing hits second?


Just some things to help me sort out.

*****

Eddit:

You can also get DR via armor through a feat (forget the name), does this stack?  Or is that DM interperitation?  What about a DR shield and armor (Adamantium Tower Shield anyone?) What's reasonable?

[SorO_Lost]

1.
If you have DR 3/-, DR 5/Cold Iron, & DR 10/Magic then...
*Getting hit with a +1 Longsword bypasses Magic, but not Cold Iron, -5 damage.
*Getting hit with a Masterwork Cold Iron Longsword bypasses Cold Iron, but not Magic, -10 damage.
*Getting hit with a +3 Metalline Longsword bypasses Magic (+enhancement bonus) and Cold Iron (property of metalline), but not the DR 3/-, -3 damage.
None of them stack, but the best applies. It's to say you have three separate Damage Reductions there, not one called DR 18/Magic or Cold Iron and -. Similarly, having Damage Reduction 3/- from your armor and 5/- from a Class Feature won't stack and only the best (5/-) applies.

However, do note there is some Class Feature/Feat based DRs that do note they stack. If they do, apply them separately. Like in the above, if that DR 3/- stacked, then a +1 Longsword deals eight less damage, -3 from the stacking DR and -5 for the Cold Iron.

2.
You are correct with your Operators.
*Cold Iron or Silver would mean either Silver or Cold Iron will bypass.
*Cold Iron and Bludgeoning would mean you need both a Cold Iron weapon and Bludgeoning damage to bypass.
 
3.
It's easier to list what Damage Reduction applies than than what it doesn't. Per Rules Compendium: "A creature that has damage reduction (DR) ignores some of the hit point damage from weapons, natural weapons, and unarmed attacks that don’t meet certain criteria." Which is semi-accurate in the details imho. DR doesn't apply against any Energy-like damage and untyped damage from spells. However, there is a few spells that deal Bludgeoning and Slashing damage, typically they note DR applies but mayhap not in every instance. A good rule of thumb for handling those is if the damage is type cast as Slashing, Piercing, or Bludgeoning, then DR should probably apply.

4.
Damage Reduction doesn't apply to Falling Damage unless you think the planet is making an attack roll using it's body as an improvised weapon. In which case I suggest you your self picking up Damage Reduction, because books may be flying in your direction. Same for Crushing damage if pinned under a house or dungeon. See the Rules Compendium entry: "A creature that has damage reduction (DR) ignores some of the hit point damage from weapons, natural weapons, and unarmed attacks that don’t meet certain criteria."

Did I cover everything?

[JaWriter]

Looks like it.  Thanks for the help.  Reinforced what we were sorting out and helps clear up the falling damage bit (RAW).

I appreciate the second voice on the matter.

[snakeman830]

It's worth noting, however, that some sources of DR/-- say they stack with class features or admantine armor, or both.  I can't recall where exactly, but I'm sure I've seen a rule stating that admantine DR stacks with Barbarian DR.  Do not use this until a quotation gets posted, however.

[Raineh Daze]

Damage Reduction doesn't apply to Falling Damage unless you think the planet is making an attack roll using it's body as an improvised weapon.

Newton's Third Law: if you hit something, it hits you back. Can I have DR against the planet, now?

... I honestly find the thought of someone dusting themselves off after falling and saying their armour absorbed it a fun mental picture, though. XD

[Jackinthegreen]

The mechanics have been explained fairly well, but there is one thing to clear up: Adamantine light armor is DR 1/-, medium is DR 2/-, and heavy is DR 3/-.  Take a look here to see it in further detail.

[JaWriter]

Good catch,

I appologise about giving incorrect numbers for light / medium / heavy types...

*flogs self with wiffle bat*

[Kethrian]

Why shouldn't DR apply to falling damage?  Would it not apply to a creature's trample, or rend, or bludgeoning damage from being swallowed whole, or other mundane physical damage source that doesn't require an attack roll?

... but not from energy attacks, spells, spell-like abilities, and supernatural abilities.

That part right there covers the things which DR does not apply to, which falling damage is none of.  It also explains that spells which do slashing/piercing/bludgeoning ignore DR, unless the spell says otherwise, because it's still from a spell.