Do Resistances Stack?

[Giant2005]

For example, an Abjuration Wizard has resistance to spell damage upon reaching level 14. If he were also a Red Dragonborn that had resistance to Fire damage and someone hit him with a Fireball spell, what would happen?
A. Half damage,
B. One-third damage,
C. One-quarter damage OR
D. No damage?

Assume he failed his reflex save in this instance please as that extra half damage just adds another level of complexity.

[GiantOctopodes]

As with most rules in this edition, it's *really* simple. You either have resistance, have vulnerability, or are neutral. If you have resistance (regardless of how many times or in how many ways you have it) you take half damage, vulnerability double damage, neutral normal damage. They are states in which you can exist, not effects that apply to damage in some sort of order. That's flat out RAW. In fact, the section on damage resistance and vulnerability on page 197 explicitly states the answer to your question, just FYI.

The only thing not expressly covered is if something has vulnerability and resistance at the same time. Let's say that a Red Dragonborn had an effect applied to him that gave him vulnerability to fire. How would those interact? Well, it won't come up too often, since not too many effects actively give vulnerability, so it's more of a theorycrafting question, but I would handle it like magnetic charges. Basically, you have Resistant (-), Normal (=), or Vulnerable (+). I would say that you add them all together, with vulnerables cancelling out resistances, so if you have two things that give resistance, but one that gives vulnerable, you are still resistant, if you have the same number of effects that apply both you are neutral, and if you have more things that give vulnerable that is what you have. However, that is purely speculation and house rules at that point.

[Giant2005]

In fact, the section on damage resistance and vulnerability on page 197 explicitly states the answer to your question, just FYI.
So it does! That rule is surprisingly detailed. Thanks for the info.


The only thing not expressly covered is if something has vulnerability and resistance at the same time. Let's say that a Red Dragonborn had an effect applied to him that gave him vulnerability to fire. How would those interact? Well, it won't come up too often, since not too many effects actively give vulnerability, so it's more of a theorycrafting question, but I would handle it like magnetic charges. Basically, you have Resistant (-), Normal (=), or Vulnerable (+). I would say that you add them all together, with vulnerables cancelling out resistances, so if you have two things that give resistance, but one that gives vulnerable, you are still resistant, if you have the same number of effects that apply both you are neutral, and if you have more things that give vulnerable that is what you have. However, that is purely speculation and house rules at that point.

I'd just ocnsider that the same as Advantage and Disadvantage - only one instance of each has any value at all and with both in play at the same time then you are back at status zero.

[Shadow]

Note that effects which lower damage taken but are not labeled as resistance apply after the resistance.
Examples:
A rogue with fire resist using uncanny dodge takes one quarter damage.
A Paladin with heavy armor mastery takes (one half damage)-3
etc

[Giant2005]

Note that effects which lower damage taken but are not labeled as resistance apply after the resistance.
Examples:
A rogue with fire resist using uncanny dodge takes one quarter damage.
A Paladin with heavy armor mastery takes (one half damage)-3
etc

That isn't actually true. That page that GiantOctopodes drew attention to covers that stuff pretty well and states that resistance is the last think to take place. It actually has an example similar to the Heavy Armor Master one that you just mentioned and the resistance occurs after the subtraction so it is (damage-3)/2 although I personally think your way is the better option and helps keep the flat rate damage reductions relevant at higher levels.

[GiantOctopodes]

Note that effects which lower damage taken but are not labeled as resistance apply after the resistance.
Examples:
A rogue with fire resist using uncanny dodge takes one quarter damage.
A Paladin with heavy armor mastery takes (one half damage)-3
etc

Not quite true. Vulnerability or resistance specifically state they apply after all other modifiers to damage. So you actually do, in your cases:
A rogue with fire resist using uncanny dodge takes one quarter damage (doesn't actually matter which one comes first)
A paladin with heavy armour mastery takes ((total damage -3)/2, rounded down as normal).

It's unlikely to make a lot of difference (specifically, in your cases, it would make exactly 1 point of damage of difference, in one instance), but I thought I'd throw it out there just as a FYI for others.

[Shadow]

It's unlikely to make a lot of difference (specifically, in your cases, it would make exactly 1 point of damage of difference, in one instance), but I thought I'd throw it out there just as a FYI for others.

I guess I was remembering it backwards.
But either way, like you said, it makes little difference.

[Celcey]

Semi-related question: If you have resistance to something and then you succeed a saving throw that gives you half damage, you take 1/4th of the total damage possible, right?

[Easy_Lee]

Semi-related question: If you have resistance to something and then you succeed a saving throw that gives you half damage, you take 1/4th of the total damage possible, right?

Yes. You get half the damage placed on the "stack", per say, and apply resistance to that. The only thing that comes after resistance is temporary hit points. Arcane ward somehow applies after AC (beneath your armor/scales) but before resistance (above your armor if the armor/scale grants resistance) at the same time, implying some sort of quantum physics.

As an exception to the answer to OP's question, certain exceptional magic items grant resistance OR immunity if you already have resistance (black dragon mask from H oRDAined), an example of how stacking might work in certain cases.

[Shining Wrath]

Yes. You get half the damage placed on the "stack", per say, and apply resistance to that. The only thing that comes after resistance is temporary hit points. Arcane ward somehow applies after AC (beneath your armor/scales) but before resistance (above your armor if the armor/scale grants resistance) at the same time, implying some sort of quantum physics.

As an exception to the answer to OP's question, certain exceptional magic items grant resistance OR immunity if you already have resistance (black dragon mask from H oRDAined), an example of how stacking might work in certain cases.

Sounds similar to the "You gain Uncanny Dodge. If you already have Uncanny Dodge, you gain Improved Uncanny Dodge instead" of the 3.5 Warblade. If you've already got it, and you get it again, you get more.

I liked Improved Uncanny Dodge. The DM played it straight and his mooks would still try to flank my Warblade even though it gave them no advantage, since the mooks wouldn't know that. Set them up so nicely for Mithral Tornado.

[Morukai]

Arcane ward somehow applies after AC (beneath your armor/scales) but before resistance (above your armor if the armor/scale grants resistance) at the same time, implying some sort of quantum physics.

The only way I can make sense of this is to say that the Arcane Ward is an external "field" of sorts, with its own set of hit points, whereas temporary hit points buffer the creature itself (which is why resistance reduces damage done to a creature, which is then subtracted from THP- but Arcane Ward takes regular damage).

Still, by descriptive fluff, it seems that Armor of Agathys should function like Arcane Ward...but it doesn't.

I find that pretty odd.

[Easy_Lee]

I liked Improved Uncanny Dodge. The DM played it straight and his mooks would still try to flank my Warblade even though it gave them no advantage, since the mooks wouldn't know that. Set them up so nicely for Mithral Tornado.

I also prefer stacking. If it comes up in my game, I'll rule resistance / uncanny dodge / whatever just gets counted twice. For resistance, that would mean 1/4 damage.

I'm also a fan of adding up adv and disadv sources and taking the higher (so darkness is no longer a neutralizer), but that's just how I roll.

[Safety Sword]

As with most rules in this edition, it's *really* simple. You either have resistance, have vulnerability, or are neutral. If you have resistance (regardless of how many times or in how many ways you have it) you take half damage, vulnerability double damage, neutral normal damage. They are states in which you can exist, not effects that apply to damage in some sort of order. That's flat out RAW. In fact, the section on damage resistance and vulnerability on page 197 explicitly states the answer to your question, just FYI.

The only thing not expressly covered is if something has vulnerability and resistance at the same time. Let's say that a Red Dragonborn had an effect applied to him that gave him vulnerability to fire. How would those interact? Well, it won't come up too often, since not too many effects actively give vulnerability, so it's more of a theorycrafting question, but I would handle it like magnetic charges. Basically, you have Resistant (-), Normal (=), or Vulnerable (+). I would say that you add them all together, with vulnerables cancelling out resistances, so if you have two things that give resistance, but one that gives vulnerable, you are still resistant, if you have the same number of effects that apply both you are neutral, and if you have more things that give vulnerable that is what you have. However, that is purely speculation and house rules at that point.

I'm not sure they would intend you counting "positives" and "negatives" and seeing what balances out. I might suggest that if you have both on the extremes the answer is that you're "neutral". That is what is done with advantage and disadvantage and that's my only "evidence".

It also fits with the pg 197 stuff. You have a vulnerability, doesn't matter how many. You have a resistance, doesn't matter how many.

If it comes up in my games I'll just cancel them out. The only way I see this being a thing is if there's a magic effect that adds a vulnerability to a resistant creature and in that case getting them to neutral is fine and reasonable.

[GiantOctopodes]

Yeah, I agree, seems easier all around and more befitting the rules. I was spitballing, but I should have remembered that spit is disgusting. :smallwink:

[Safety Sword]

Yeah, I agree, seems easier all around and more befitting the rules. I was spitballing, but I should have remembered that spit is disgusting. :smallwink:

You can play your magic elf game with or without spit. Totally up to you.

[Shining Wrath]

You can play your magic elf game with or without spit. Totally up to you.

I'm sorry, but I'm pretty certain that by RAW certain MM monsters do, in fact, spit. It is not possible to have a loogie-free magic elf game.

[Safety Sword]

I'm sorry, but I'm pretty certain that by RAW certain MM monsters do, in fact, spit. It is not possible to have a loogie-free magic elf game.

Some DMs just clearly use monsters with higher standards than others. :smallamused: