Percentile (Dynamic) Damage Reduction

[MrFix]

Are there any rules in GURPS for percentile damage reduction? By that I mean, instead of set DR number, you have DR percentage like 25%, and all damage that DR protects from is reduced by 25%.

For example. A Fire Protective Suit has DR fire 50%. A character wearing it enters fire that deals 3d (average 10.5) every second. Due to his DR, he only suffers 5.25 average damage. If the fire instead dealt 1d (3.5 average) per second, he'd only suffer 1.75.

I am mainly interested in pricing of such DR, if there are any caveats etc, maybe even converting static DR to this dynamic DR.

[coronatiger]

My first thought was to estimate average amount of damage prevented, and base the cost on that. E.g. if you can predict that most fires will deal 3d damage and you reduce damage by 25%, then you need to buy the equivalent of DR 3. (25% of average 10.5, rounded up.)

[Anthony]

Originally Posted by MrFix

Are there any rules in GURPS for percentile damage reduction? By that I mean, instead of set DR number, you have DR percentage like 25%, and all damage that DR protects from is reduced by 25%.

Injury Tolerance (Damage Reduction) divides damage taken by a specific number, and you can extrapolate numbers further. You can also apply Limited (Will Only Stop Up To X%) to DR, though there is no standard price for that.

[Plane]

Originally Posted by MrFix

Are there any rules in GURPS for percentile damage reduction? By that I mean, instead of set DR number, you have DR percentage like 25%, and all damage that DR protects from is reduced by 25%.

For example. A Fire Protective Suit has DR fire 50%. A character wearing it enters fire that deals 3d (average 10.5) every second. Due to his DR, he only suffers 5.25 average damage. If the fire instead dealt 1d (3.5 average) per second, he'd only suffer 1.75.

I am mainly interested in pricing of such DR, if there are any caveats etc, maybe even converting static DR to this dynamic DR.

Powers has "Injury Tolerance: Damage Reduction" which divides the Penetrating Damage (after subtracting your DR from Basic Damage) so you suffer fractional wounds.

That sort of sounds like what you're going for.

If you want it divided prior to hitting DR that's a cosmic modifier on either the DR or the ITDR, forget which.

[Taneli]

As others have said, IT: DR divides damage after DR but before injury multiplier, whereas IT: DR (Cosmic, divides damage before DR) divides damage before DR.

It's unfortunate that we have these traits with rather similar names.

Anyhow, I don't know if percentile DR makes sense for realistic things. For supers and other handwavey stuff, sure why not?

[JulianLW]

Ummm...

I'm not great at math or anything, but Injury Tolerance: Damage Reduction of 50% already has a price. It's IT:DR 2 for [50]. Damage Reduction 66% already has a price: IT:DR 3 for [75]. 75% is IT:DR 4 for [100]. All of this is on Powers 53.

Supers expands the range of Injury Tolerance: Damage Reduction. 80% is IT:DR 5, for [125]; 90% is IT:DR 10 for [150], and so on. 99% is IT:DR 100 for [300].

It's not listed anywhere, but it seems reasonable (though almost certainly not cost-effective compared to regular DR or HP) to price Damage Reduction of 25% - which would be (I guess?) IT:DR 1.3333 (it'd be easier to multiply damage by 3/4 than apply 1.3333 as a divisor) - at [25], since it'd be half the damage of IT:DR 2 at [50].

I don't know about applying Cosmic to IT:DR so that it reduces damage before regular Damage Resistance. I've never seen that anywhere, but I'd be interested to know if that's been published somewhere.

Maybe I've misunderstood the question here about the interaction between IT:DR and regular Damage Resistance?

[MrFix]

Cheers for the replies, I am especially interested about the Cosmic part where IT:DR applies to original damage, rather than penetrating, so if it is published somewhere, please post the reference.

[Plane]

Originally Posted by MrFix

interested about the Cosmic part where IT:DR applies to original damage, rather than penetrating, so if it is published somewhere, please post the reference.

It's not mentioned on P53's intro of the advantage, P118 extends the divisors w/ cost and P119 mentions the cosmic enhancement.

This is one of those "we're not told the technical name of how to list this cosmic variation" situations, so Taneli's nomenclature is sort of guessing at how to represent it...

The technical phrasing is "only suffer this if the injury is at
least 1 HP after applying the divisor" in respect to "Minimum injury from an attack that pierces DR is always 1 HP"

That technically doesn't say you divide it before applying DR, just that you round fraction of Penetrating Damage less than 1 down instead of up.

Fractions higher than 1 always get rounded down already, there's just a special rule about rounding sub-1 fractions up which gets ignored here.

So for other purposes (for example how much Ablative DR is lost, how much Knockback you suffer) I don't think this technically reduces it in any way.

That can be a good thing if you have Absorbtion or Reflection though, since dividing Basic Damage before it hit DR could reduce the amount of damage you benefit from or send back

[Anthony]

Originally Posted by MrFix

Cheers for the replies, I am especially interested about the Cosmic part where IT:DR applies to original damage, rather than penetrating, so if it is published somewhere, please post the reference.

There's no published version that does that -- there's a published version that eliminates the minimum damage 1 rule (that version is in Powers).