Damage types and resistances: Creating a single, consistent house rule for my game.

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Anyone who hangs out Rules Q&A sees the "What happens when I take 3 untyped damage, 4 Fire damage, 2 Radiant And Cold damage, and have Resist 5 Fire and Resist 5 Cold and Resist 4 All and Vulnerable 5 Cold?" question and the accompanying "Nobody knows.  Here are some options" answer regularly.

I want a solid answer for my game.

So, here it is:  I define a term "damage instance".  A "damage instance" is a single set of single-typed damage, from a "damage package" which is the damage dealt by a single source.

So the attack from my example, "3 untyped damage, 4 Fire damage, 2 Radiant And Cold damage", is one damage package that has three damage instances:  untypes, Fire, Radiant And Cold.

The rules:

1A:  A single Resistance may apply to one and only one damage instance.  Only one resistance may apply to a damage instance.  (There is an exception to this for multi-typed damage:  Multiple resistances apply, take the lowest)
1B:  A single Vulnerability may apply to one and only one damage instance.  Only one vulnerability may apply to a damage instance.

2A:   A resistance applies only if it's type matches the damage instance type exactly.  Multiple resistances can "combine" to resist multiple-typed damage.
2B:  A vulnerability can apply if it's type matches the *any* of the types of the damage instance, and the extra damage is of all the types of the instance

3A: Resistances apply in the way that most favours the DEFENDER - so if there are two ways to arrange resistances, the one that results in the least damage getting through is the one you use.
3B: Vulnerabilities apply in the way that most favours the ATTACKER - so if there are two ways to arrange vulnerabilities, the one that results in the most damage getting through is the one you use.

4:  Resistances and vulnerabilities apply simultaneously.

5:  None of the other rules for Resistances have been changed - so you can't have "Resist 5 Fire two times and Resist 10 Fire" and use one to stop Fire, one to combine and stop Fire And Cold, and one to combine and stop Fire And Radiant, not even if you have three different sources of Resist Fire.


Applying these house rules, we take my example:
"What happens when I take 3 untyped damage, 4 Fire damage, 2 Radiant And Cold damage, and have Resist 5 Fire and Resist 5 Cold and Resist 4 All and Vulnerable 5 Cold?"

And we get one and only one correct answer.

Dividing into Damage instances, the attack has three instances:
3 Untyped
4 Fire
2 Radiant And Cold

We have one Vulnerability to apply to one of the instances:
Vuln 5 Cold

We have three Resistances to apply to the instances:
5 Fire
5 Cold
4 All

We start by discarding the Resist Cold since it can't apply to anything, not even in combination.

Resist Fire applies to the Fire Damage
Resist All can apply to either the Radiant And Cold or the Untyped damage.
Vulnerable Cold applies to the Radiant And Cold.

Our only choice, then, is where to apply the Resist All - and we get the best results by applying it to the Radiant And Cold, where it will eliminate 4 damage (with the Vulnerability) rather than the Untyped where it will only eliminate 3 damage.

So our final answer is:
3 Untyped
0 Fire
3 Radiant And Cold


So:  That's my house rule.  Divide up the damages, divide up the resistances, divide up the vulnerabilities, apply them all in the way that most favours the attacker and defender while never applying the same one to more than one instance, or more than one[1] to the same instance.

I think this works.
I can't think of any *broken* situations with this.
I can't think of any confusing situations with this, that will take more than a few seconds to resolve.
I think this gives the best of all worlds in terms of letting people be awesome and making the most effects apply.

Your turn:  PEACH.  Tell me where this breaks down, or why I shouldn't make this my default handling of all Resist/Vuln/Whatever questions.

[1]:  Again, the exception for combining resistances to multi-typed damage applies.

Update 8/25:  I have swapped the words "package" and "instance"  - a "package" now contains multiple "instances", not the other way around.  Because that makes more sense to me.  I've also added Rule 5 in response to Movanic's feedback, to clarify that you can't have more than one Resist Foo.
Confused about Stealth? Think "invisibility" means "take the mini off the board to make people guess?" You need to check out The Rules Of Hidden Club.
Damage types and resistances: A working house rule.

Looks fine if your group is math-empowered.


As a gut feeling, this will end up making stacking resistances very valuable - even more so than now. But that's just my gut.


Quick question : if you need to combine resistances, are they both "expended" ?


Ex: 2 fire-radiant and 3 fire-cold damage packets are coming your way. You have resist 5 cold, fire, radiant. Is it all resisted or did you "expend" fire resistance when combining it with cold ?


If you "expend" it, would it then be possible to have multiple sources of resist as "back-up shield generators" ? If so, would effects that now add to your resistance be considered a second source ? Would they apply to both ?


Querries, querries... seems like your "no possible confusion" has met its match! (Note: I've yet to see a situation over which I could not confuse myself. It's a gift. Not a great one mind you... Hum, you have any to trade for mine, by any chance ?)

Looks fine if your group is math-empowered.

We're pretty quick about it.  And situations as complicated as that example are *rare*.  Much more common is "6 untyped and 3 Fire, I have resist 5 Fire and 2 All, what do I take?" - which is also unclear under the RAW.


Quick question : if you need to combine resistances, are they both "expended" ?


They are.  Each resistance may apply to only one damage package.


If you "expend" it, would it then be possible to have multiple sources of resist as "back-up shield generators" ? If so, would effects that now add to your resistance be considered a second source ? Would they apply to both ?


Resistances do not stack and you can't have "Resist 5 Fire twice", under the main rules.  I haven't changed those, so you can't do it now.


Your items and Feats and Backgrounds and Powers and all the rest set your resistances, but those are all set and simplified before you start worrying about damage.


Querries, querries... seems like your "no possible confusion" has met its match! (Note: I've yet to see a situation over which I could not confuse myself. It's a gift. Not a great one mind you... Hum, you have any to trade for mine, by any chance ?)



Those are good questions, thanks for the feedback.
Confused about Stealth? Think "invisibility" means "take the mini off the board to make people guess?" You need to check out The Rules Of Hidden Club.
Damage types and resistances: A working house rule.
Quick question: IIRC by the rules a vulnerability and a resistance of the same type should be subtracted from each other. So the actual resistance to cold should be canceled by the vulnerability to cold. Is this right?
Quick question: IIRC by the rules a vulnerability and a resistance of the same type should be subtracted from each other. So the actual resistance to cold should be canceled by the vulnerability to cold. Is this right?



Not exactly:  Someone who is both Vuln 5 Cold and Resist 5 Cold will take 0 additional damage from cold attacks after both apply, but they *are* still both Vulnerable and Resistant - so people with the Wintertouched Feat will get Combat Advantage against them, a Sorcerer who ignores 5 Cold Resistance will ignore the Resistance and still get the bonus from the vulnerability.
They'll cancel each other's effects out most of the time, but they won't REMOVE each other, if you see what I mean?


The interactions of vulnerabilities with multi-typed damage is not defined, RAW.  The way I've defined it here, the cold vulnerability applies to the Radiant And Cold damage, and adds Radiant And Cold, which the Resist Cold can't touch anyway.
Confused about Stealth? Think "invisibility" means "take the mini off the board to make people guess?" You need to check out The Rules Of Hidden Club.
Damage types and resistances: A working house rule.
Yeah but that doesn't make sense IMO.

The rationale of the "lowest resistance applies, highest vulnerability applies" rule of the multitype attacks is that, even if you resist the cold damage, you're still getting the radiant part. Now, if you resist some of the cold damage, but still take the whole damage because you're not resisting the radiant part, how come the vulnerability to cold comes in play in full effect?

In fact, I vaguely remember a rule that said you had to subtract vuln. and res. of the same type before accounting for the multi-typed damage. And if there isn't, there should be.
Yeah but that doesn't make sense IMO.

The rationale of the "lowest resistance applies, highest vulnerability applies" rule of the multitype attacks is that, even if you resist the cold damage, you're still getting the radiant part. Now, if you resist some of the cold damage, but still take the whole damage because you're not resisting the radiant part, how come the vulnerability to cold comes in play in full effect?



Short version:  Because I like it better that way.   I figure if you've gone to the work of inflicting a vulnerability and then hitting it with multi-typed damage, that's worth something.

Longer version:  You *could* have the vulnerability add damage of it's own type - causing, in my example, "5 Cold And Radiant" to become "5 Cold And Radiant and 5 Cold" instead of "10 Cold And Radiant".  At which point, sure, your Resist Cold would kick in again.

But you'd still be Vulnerable Cold and Resist Cold for effects that key off those states, and things that modify them.  Simply adding Resist 5 Cold does *not* mean that a Wintertouched character loses CA against you from your Vulnerable 5.

In fact, I vaguely remember a rule that said you had to subtract vuln. and res. of the same type before accounting for the multi-typed damage. And if there isn't, there should be.



There's no such rule, because there are no rules about multi-typed damage and vulnerability at all.  There *IS* no official rule on how it works - which is why I've got my house rule here.
Confused about Stealth? Think "invisibility" means "take the mini off the board to make people guess?" You need to check out The Rules Of Hidden Club.
Damage types and resistances: A working house rule.


In fact, I vaguely remember a rule that said you had to subtract vuln. and res. of the same type before accounting for the multi-typed damage. And if there isn't, there should be.



There's no such rule, because there are no rules about multi-typed damage and vulnerability at all.  There *IS* no official rule on how it works - which is why I've got my house rule here.



I thought your house rule was for claryfying corner cases.

Anyway, turns out I am right. There are rules for multityped damage and they work exactly as I said. Check for yourself.



Rules Compendium page 224
Against Combined Damage Types
A creature's resistance is ineffective against combined damage types unless the creature has resistance to each of the damage types, and then only the weakest of the resistances applies.

 
 

Rules Compendium page 225


Combined with Vulnerability


If a creature has resistance and vulnerability to the same type of damage, they both apply. Subtract the smaller value from the larger one and apply the result. For instance, a creature that has resist 5 fire and vulnerable 10 fire is treated as if it has vulnerable 5 fire.


 

Rules Compendium page 225


Combined with Vulnerability


If a creature has resistance and vulnerability to the same type of damage, they both apply. Subtract the smaller value from the larger one and apply the result. For instance, a creature that has resist 5 fire and vulnerable 10 fire is treated as if it has vulnerable 5 fire.




This is one of the many reasons I hate the Rules Compendium.  So many rules were pointlessly, ignorantly rewritten in ways that are stupid, inconsistent, and make no sense.  The purpose of the book was to reprint the rules with the changes added, so WHY did some idiot go through and add uncertainty and inclarity to previously working passages?


Take that one, for example:  Is they both apply true, or is a creature that has resist 5 fire and vulnerable 10 fire is treated as if it has vulnerable 5 fire true?

They can't BOTH be true - consider what if you had something that said "creatures who resist Fire add 5 to their Resistance" - should that apply, because both apply and it has Resist Fire, or should it not apply because it is treated as if it has Vulnerable 5 Fire.

Consider a Sorcerer who ignores up to Resist 10 Fire, against someone who has Resist 5 Fire and Vulnerable 10 fire.  If they both apply, he ignores the Resistance and gets the +10 damage from the vulnerability.  If it is treated as if it has Vulnerable 5 Fire he gets only +5 damage.

Or take Resist Cold 10, Vulnerable Cold 5, and Wintertouched.  If they both apply is true, a Wintertouched character gets Combat Advantage with his Cold attacks, but gets 5 damage knocked off.  If it is treated as if, he doesn't get Combat Advantage.

In short, the example there doesn't match the rules text.  And since the example doesn't match the rules text, the only correct response is to consider the example to be invalid, just like you don't take a fluff description over rules text.
Confused about Stealth? Think "invisibility" means "take the mini off the board to make people guess?" You need to check out The Rules Of Hidden Club.
Damage types and resistances: A working house rule.
Also:

I thought your house rule was for claryfying corner cases.
 


No, it's for covering non-covered cases:  Specifically, when multiple resistances can apply to multiple different damage types being dealt at a single time.

That's a "corner case" only because nobody ever printed an official rule for what happens when "Resist 5 All" meets "5 Cold, 5 Fire, and 5 Untyped damage"
Confused about Stealth? Think "invisibility" means "take the mini off the board to make people guess?" You need to check out The Rules Of Hidden Club.
Damage types and resistances: A working house rule.
1. This was errataed way before the RC came out. Like one year or something. It's not the RC's 'fault', it didn't change anything. On an errataed PHB you would find the same exact rules.

2. Both of your concerns are explained below:


  • First, it says that they both apply, and then goes on explaining what does it mean with they both apply, so it's true that it is treated as if.  You are taking they both apply as you apply the resistance and the vulnerability separately, while it's just a paragraph-opener way to introduce the following sentence. Ok, it's not extra clear, but you can't treat sentences as unrelated to each other. 

  • Second, if you take that paragraph in the context of the section, it is clear that the it is treated as if only applies to damage. First the sorcerer ignores the resistance, then only the vulnerability remains. At this step you would apply the it is treated as if, but there is only a vulnerability and so the sorcerer gets +10 to his damage.


Ok, it could be much clearer than it is, but the rules IMO are unambiguous. In fact, I thought that the reason for this thread was clarifying corner cases and unclear situations, since the rules are not as clear as they could be on some points.
1. This was errataed way before the RC came out. Like one year or something. It's not the RC's 'fault', it didn't change anything. On an errataed PHB you would find the same exact rules.



Not true.  The wording from the updated PHB is simpler, clearer, contains no contradictions.... and doesn't indicate what kind of damage the increased damage from vulnerability to multi-typed damage is.  Nor does it ever indicate that Resist and Vulnerability will cancel each other out while still "both applying" like the RC does.

The RC example is bad, and poorly written.  The PHB rules are incomplete.  Neither one tells completely what to do in the "vulnerable to multi-typed damage" case, and neither one addresses multiple resistances to damage of multiple separate types from the same source.


2. Both of your concerns are explained below:


  • First, it says that they both apply, and then goes on explaining what does it mean with they both apply, so it's true that it is treated as if.  You are taking they both apply as you apply the resistance and the vulnerability separately, while it's just a paragraph-opener way to introduce the following sentence. Ok, it's not extra clear, but you can't treat sentences as unrelated to each other. 

  • Second, if you take that paragraph in the context of the section, it is clear that the it is treated as if only applies to damage. First the sorcerer ignores the resistance, then only the vulnerability remains. At this step you would apply the it is treated as if, but there is only a vulnerability and so the sorcerer gets +10 to his damage.


Ok, it could be much clearer than it is, but the rules IMO are unambiguous. In fact, I thought that the reason for this thread was clarifying corner cases and unclear situations, since the rules are not as clear as they could be on some points.



I believe that you can, by turning your head and squinting, read the RC rules the way you have read them.

I do not believe that they are clear or unambiguous, in the way that the PHB rules were, and I don't see where in the RC document it says *what damage type* multi-typed damage increased by a Vulnerability to one type is.
Confused about Stealth? Think "invisibility" means "take the mini off the board to make people guess?" You need to check out The Rules Of Hidden Club.
Damage types and resistances: A working house rule.
MMh, I checked the PHB rules and the only difference is the Combined with vulnerability paragraph missing. So there is no real difference in wording, just one paragraph missing. BTW I checked on the Online Compendium and it's missing there, too, so I have to give you this one.

Anyway, fair enough. You can see just by the fact we're arguing that the rules are not clear on this point and need a rewording. Bonus point for the Monkey Island 3 quote (if it was intended).

I still think the paragraph in the RC should be taken in consideration when doing the actual rewording. The way you've done it, it's actually counterintuitive that the vulnerability applies to the multitype damage without being first affected by the resistance. I believe that resistances and vulnerabilities of the same type should be subtracted from each other before calculating damage.

I still think the paragraph in the RC should be taken in consideration when doing the actual rewording. The way you've done it, it's actually counterintuitive that the vulnerability applies to the multitype damage without being first affected by the resistance. I believe that resistances and vulnerabilities of the same type should be subtracted from each other before calculating damage.



That's fair enough, and you could easily do it that way.

I didn't, because vulnerabilities are harder to inflict than resistances are to get, and I try to err on the side of having powers (both PC and monster) do more, not less.
Confused about Stealth? Think "invisibility" means "take the mini off the board to make people guess?" You need to check out The Rules Of Hidden Club.
Damage types and resistances: A working house rule.