Sort of in response to another thread on the forums. But this time, I’m wondering if I can use my favorite thing in the whole ** GURPS **world to answer a question about scaling DR with tech level.

**Damage Resistance**

At 5 points per level, DR is fairly expensive. It’s 1.6x more than Fatigue Points and 2.5x more expensive than HP, and half the cost of ST. If we take the baseline for the cost of this trait as generically fair, then it takes 17.5 points to be protected vs each die of damage. So for 18 points you are immune to the average barehand thrust damage for a ST 14 warrior, and for 35 points you’re immune to swing damage of 2d. Thus to be protected from typical pistols is going to be in the 35-50 point range, and over 100 points to shrug off a rifle.

Buying enough DR to deal with a 6dx30(3) tank projectile is thus 90x more expensive, or about 9,000 points.

That’s a lot of points. Probably too many, since diminishing returns should set in somewhere.

**Diminishing Returns or by Tech Level?**

Diminishing returns brings up a good point. While I started with “scale it by Tech Level,” it might be better just to bend the cost curve. Let’s see . . .

*By Tech Level*

Scaling by Tech Level assumes that you’ll be bending the curve by the average or typical threat a PC is likely to face. Maybe 1d-3d at TL3, 3d-8d at TL8, and reaching for blasters and such, something like 12d-18d at TL10, including the effects of armor divisor. A quick scatterplot shows that, well, shucks, the scaling for a power law seems to go at the 1.45 power of Tech Level, which means scaling protection by the Size and Speed Range table (which goes as the sixth root of 10, or 1.468) will give pretty decent results. If we assume DR cost is scaled for the value of a TL3 world, then you can multiply the effect of DR by how many steps up the S/SR table you go, at roughly x2 per 2TLs.

In short, if it costs you 35 points to be protected vs a 2d attack (DR 7) at TL3, that same 35 points will buy you 3d at TL4, 10d at TL7, 14d (about enough to bounce a .50 BMG) at TL8, and 6dx5 (DR 105) at TL10.

Note that the offset for paying 35 points for DR 50 at TL8 is an Improved Assault Vest and SAPI inserts, which provide DR 47 to the torso front and rear for $3,600 and 26 lbs. So it’s basically 35 points to have, all the time, what you can have if you can buy the stuff and carry the weight.

If you drop 100 points of “unfairness” into DR, the same cost as ST 20 or Altered Time Rate, you will wind up with DR 20 at TL3, DR 140 at TL8, and DR 300 at TL10. Compare with armor and battlesuits in the DR 60-150 range at TL10.

*Diminishing Returns*

The other way to go here would be to forget TL and just say that, much like ST in a way, once you have more than enough, the marginal value of more is zero.

T-Bone has the best suggestion for pricing ST I’ve seen. Applying that philosophy to DR would make some sense. The ST progression works out great, and provides a great diminishing returns once you get out of human norm.

Well, there is no human norm for DR, and direct conversions with Thomas’ table won’t really work . . . but if we say that each 25 points is 2 steps up the Size and Speed/Range Table, we get something like a decent progression, where the cost of DR is 5 points per level up to DR 10, and then each 25 points takes you two steps up the S/SR progression, or 150 points per x10, which not coincidentally is half the increment for the ST table in T-Bones’ rules.

**Parting Shot**

The two options to not produce equivalent results. DR 1000 at TL8 (285d+2) using TL scaling is about 700 points, while DR 1000 using diminishing returns is only 200 points. That being said, against an AP attack such as DU, that’s 6dx15 (3) or perhaps even more importantly, about 6dx5 (10), which is not out of line for a shoulder-fired ATGM at TL8 (see GURPS High-Tech, p. 148 for some examples). If people are known to be that tough, tough weapons will be deployed against them.

The same 200 points of ST will buy ST 50 using those rules, while 700 points will purchase about ST 2,000. Relative to DR 1,000 the 700-point cost for ST and DR might balance “better,” but really, at that point level you’re pricing against the cost of equipment.

I think ultimately, the linear cost for DR needs to somehow become diminishing as either protection scales up, TL scales up, or maybe even both. DR 1,000 at TL3 is basically untouchable without cosmic attacks or things that blow right through DR like Deathtouch (I think). DR 1,000 at TL8 means that you’re in the same class as a decent armored vehicle remembering that an M1A2 or Leopard 2A6 might well be in the neighborhood of DR 5,000 against HEAT attacks, and 2,500 against “mundane” KE attacks.

Some sort of blend, where DR gets a multiplier per point based on the TL/typical threat, but also has a diminishing returns progression, might wind up being the best. No firm judgement yet on my part – but some noodling provided at least some guidance. I”d expect 500-1000 points to be at least as good as a modern MBT, which means with “only” a 7x multiplier for TL, you still need some sort of diminishing returns to get you there.

More later, I’m sure!

DR scaling that follows logarithmic curve should have the same cost as IT(DR) that follows an exponential curve, since IT(DR) is basically log pricing on hit points. Assuming you don't consider IT(DR) overpriced, 25 for 2 steps on the range/speed chart seems much too fast.

Alternately, IT(DR) (Cosmic: applies before natural DR) solves both DR and Hit Points.

Only covers Dr and possibly ST, I would like a more generic solution though.

What about running some numbers using campaign starting wealth.

Determine primry weapon or maybe an average per TL and figure the cost as a % of starting wealth.

I suspect we wont get consistent numbers but if we do maybe that can be worked into a formula useful for all advantages that can be replaced by gear.

I know the idea of being "immune to damage" is anathema in GURPS, but have you tried working this backwards? Start with what you feel not getting hurt should cost in relationship to other things, and work the curve backwards from there? You're DR 1000 vs. a shoulder-fired AP round doing 6dx5 (10) kind of hints that you think Impervious to Damage should have a value, or at the least, is less pricy than DR 1000 under what you proposed here. You've done a scatterplot of "typical" weapons; what about atypical weapons at the top end of their TL?

I do like the idea you have here, and a blend of diminishing returns and TL produce a really nice. I'm curious to see any followup you put together.

I'm presently running a supers game, 100pt base + 200pt superhero template designed by me (so that nobody sucks) + 200pt power designed by a different player. Mind Control for 50 points is scary to any government, mind-reading and clairvoyance almost as bad, Warp with Tunnel and extended duration puts you on the A-list too, and a 1pt toxic attack enhanced to cover a large city from the other side of the world makes you the equivalent of a nuclear power. 200 points in ST makes you as strong as a forklift, and 200pts in DR makes you as tough as one. There are plenty of forklists. And this is for a guy who goes down easy for the mind controller or the toxic attack guy (if one of the enhancements is Ignores Armor, or maybe Mental Defense Only). So I'm using a rule that cost is normal to level 27, then the formula goes (level-25)^2/2+25 (rounded up)…chose the breakpoint so that every level of ST you buy increments damage, and just used the same for DR (and the ST-based component of TK). Don't need it for innate attacks – enhance with armor-piercing instead.

On the subject, Doug, I've been meaning to challeng you to this exercise: Build a brick, ST 100 say, or ST 1000, with Constriction Attack (or Trained by a Master) for double cp. What's a good target level of DR and Control Resistance so he can stand up to more than one grab'n'smash attack from his evil twin? What limitations would you apply? What I keep coming up with, is that DR is the better buy, and he winds up with so much that he wouldn't even feel a punch from his nemesis.

I don't much care for either method you've presented. How useful traits like DR or Innate Attack are varies by the content of the game world, and since GURPS is universal, that could mean a world populated by nearly anything. Wizards might regularly shoot 6d wands at you in a world with hundred-foot-tall giants stomping for a thousand dice of damage. The only way I can make sense of the trait pricing in that world is to have the GM base the price on what sorts of enemies he expects to throw at you, since the utility of the DR will vary wildly from world to world and not correlate with something like TL or relation to a logarithm.

What I recommend is selling the DR based on how much protection it represents in the game world. Something like this:

Trivial [1]

Minor [5]

Low [25]

Medium [50]

High [100]

Extreme [250]

Ridiculous [500]

Unbelieveable [750]

Absolute [1000]

So a high level of DR is always a hundred points, but what that means varies by the threats the GM expects to throw at you. In a TL3 fantasy game, the amount of DR that gives will be completely different from a TL12 game where the characters are sapient spaceships who shrug off primitive hydrogen bombs like pebbles thrown by toddlers.

With this method, it would be up to the GM to decide what the actual DR levels are, but it should be easy enough to come up with guidelines and suggestions.

DR (and innate attacks) are two of the most obvious traits that have issues with setting scaling and diminishing ROI, but it is a problem with GURPS in general. GURPS tries to be Universal by swag-ing this in various ways, but if I wanted to "fix" it I'd break out the issues separately:

I. Availability: Any ability that can be replicated for $ in the setting should probably get a discount. Base this off of the Addiction Disad to account for availability, with a side order of the payload advantage (and lifting ST) to carry it.

II. Stack-ability. Most commonly seen with DR. Stuff that adds to or multiplies with equipment in the setting is better than innate substitutes that don't.

III. Diminishing returns: Also setting based, since when kill becomes overkill depends on what it takes to kill in the first place.

A veritable bait shop of worms, but well worth fixing if you get a good fix.

Bear in mind a lot of enhancements will need tweaking – if you're using diminishing returns for costs on DR a percentage enhancement for hardened defenses doesn't really work any more. There's some discussion of scaling innate attacks, DR. etc starting about here – http://forums.sjgames.com/showpost.php?p=1753478&postcount=30 – in this thread. My post in #41 gets the math wrong for scaling Injury Tolerance (Damage Reduction) – if it is to match the every 300 points gets 10x ST scale, every 60 points should get you IT(DR) of 1/10.

What might be simplest is a scale multiplier. Since DR costs 2.5 what hit points do, that suggests multiply DR by 10 for every 150 points. So for 25 points, multiply DR by 1.5, For 50 points, multiply by 2, etc, Scale becomes cost effective around 15-20 DR. Calculate the cost of any enhancements on DR before adding in the effect of scale.