Saves, Resistance, and Vulnerability

So my players tossed a fireball at a Frost Giant that was wearing a ring of fire resistance (minor). Here's how I processed it:

Player rolled 5d6 and came up with 17 pts for damage.
The FG made its save, reducing that to 8 pts of damage.
The Ring absorbed all 8 of those pts.
There was no damage left to be multiplied by 1.5 for the vulnerability to fire.

The player accepted the ruling (i.e. wasn't excessively argumentative) but put forth the position that the vulnerability should have applied before the ring subtracted damage, i.e. 17 (/ 2 for save) = 8 (* 1.5 for vulnerability) = 12 (- 10 for ring) = 2 pts damage.

How would you run it? As this example demonstrates, the order in which you apply these elements can lead to a variety of results. My logic was:

First, save reflects how well you avoid the fireball, which determines the amount of fire to which you are initially exposed.

Second, the ring "continually protects the wearer from damage...Each time the wearer would normally take such damage, subtract the ring’s resistance value from the damage dealt" (from SRD). I take this to mean that the damage is subtracted before the target is subjected to it, so that the last thing to apply is...

Third, the vulnerability applies to the damage that you don't avoid and that isn't absorbed by the ring.

The players and I agreed in the end that it depends on whether you see the ring as preventing 10 pts of damage in the first place versus negating damage that is taken, for instance by instantly regenerating it. The former suggests the ring goes first while the latter suggests that the vulnerability applies first.

I wanted to know what people on the board think.

Thanks,
MC

I actually don't think there's anything in the rules about this, but I would say that you should multiply first and let the resistance absorb later, just as if it had been a critical hit versus a creature with DR.

i.e.

1. Saving throw
2. Vulnerability
3. Resistance

The DMG p.291 (or the MM) covers this under Cold Immunity: "...It has vulnerability to fire, which means it takes half again as much (+50%) damage as normal from fire, regardless of whether a saving throw is allowed, or if the save is a success or failure."

Sure looks like the total damage rolled is first increased by +50%, halved by a successful saving throw, and then fire resistance is applied.

Henrix said:

I actually don't think there's anything in the rules about this, but I would say that you should multiply first and let the resistance absorb later, just as if it had been a critical hit versus a creature with DR.

Click to expand...

I think this is a useful comparison, and a reasonable way to approach it On the other hand, extra critical damage is based on how well the attacker hits, regardless of any characteristics of the target (other than immunity to crits, of course). So it seems necessary that crit damage apply before DR, whereas I'm not sure when both a damage increase and a damage increase are due to qualities of the target.

Liquidsabre said:

The DMG p.291 (or the MM) covers this under Cold Immunity: "...It has vulnerability to fire, which means it takes half again as much (+50%) damage as normal from fire, regardless of whether a saving throw is allowed, or if the save is a success or failure."

Sure looks like the total damage rolled is first increased by +50%, halved by a successful saving throw, and then fire resistance is applied.

Click to expand...

We looked at that but unfortunately I don't think it addresses the issue either way, because if you're only considering saves and vulnerabilities, not resistances (which is true for that DMG/MM quote), it doesn't really matter. dmg * 1.5 (vulnerability) * .5 (save) = dmg * .5 (save) * 1.5 (vulnerability) = dmg * .75. Granted, which you do first could make 1 pt difference due to rounding down. But in any case, I don't see how the quote implies order--it just says the +50% applies whether or not you make the save. You could apply it before or after save results and the result is the same.

Resistance is applied last (just before the creature takes damage) and a frost giant normally takes x1.5 fire damage with or without a ring, or with/without a save. Simply just count all fire damage as x1.5 (and forget the original damage, as it doesn't exist for a creature vulnerable to fire). The ring won't change the giant's vulnerability to fire, so the ring protects the giant from the first 10 points of damage the giant would normally receive (x1.5).

So it goes:

17 points of damage (x1.5) = 25 (rounded down)
Successful Reflex Save = 0.5 x 25 = 12 points of damage (rounded down)
Ring of Fire Resistance = 12 - 10 = 2 points of damage received by the frost giant.

Now my only question here is, what was a 5th level wizard and their party thinking when trying to take on a frost giant!?

Liquidsabre said:

Now my only question here is, what was a 5th level wizard and their party thinking when trying to take on a frost giant!?

Click to expand...

Actually, it was the Rog4/Ftr4 who cast a 5-die fireball from a scroll. The other party members are a Ftr7 and Wiz6/Clr2, and they faced not only the frost giant but also 4 Snow Apes (OD&D-based, but let's call them CR 2 each) and an Ice Wolf (basically a Winter Wolf but not smart). How could they possibly survive this encounter (which was an ambush, by the way)? Well, it helps that they had an adolescent stone giant (stats between hill giant and stone giant) on their side for this fight.