From Abilities to Skills
 

In Pyramid 3/44, Dr. Kromm has an article ("From Skills to Advantages") that Shows how one might turn a cinematic skill into an advantage. (Short version: figure out how much the skill would cost at Attribute+0 level, then say that it's an advantage that costs that many points and works just like the skill does, but requires an attribute roll to use successfully.) I'd like to experiment with doing things the other way around: start with an Advantage; apply a set of Enhancements and limitations to it until it requires an Attribute roll to use it and costs as much as a skill would at the Attribute+0 level; then declare it to be a (cinematic) skill.

So, for example: start with Medium. This 10-point Advantage lets you perceive and communicate with spirits, and to call them (though they're not forced to answer the call). No roll is required, nor is any effort needed to maintain it. How would we turn this into a Skill?

First, determine how much Limitations are needed. An Easy Skill costs 1 point to use at its base value; an Average Skill costs 2 points; a Hard Skill costs 4 points; and a Very Hard Skill costs 8 points. These require -90%, -80%, -60%, and -20%, respectively. Since you can't have more than -80% worth of Limitations, we have to make it at least Average difficulty.

Second, apply some Limitations. We need it to be based on an Attribute roll, so we'll start with "Requires (Attribute) Roll". The attributes that make the most sense are IQ, Per, and Will: IQ would count as a -10% Limitation while each of the other two would count as a -5% Limitation. Adding a Fatigue Cost is recommended, so that you can't make the roll once and then leave it on more or less indefinitely; -5% per FP if you have to maintain it every minute, and -10% per FP if you have to maintain it every second. Alternately, it might Require Concentration to maintain (-15%). Finally, Preparation Required is highly appropriate for converting Medium into a "Séance" skill: that's -20% for 1 minute, -30% for ten minutes, -50% for one hour, and -60% for eight hours.

So let's go with a Per roll (-5%), Requires Concentration (-15%), and Preparation Required (one minute, for -20%). That brings the cost down to 6 points, half-way between the costs of Hard and Very Hard. Let's add an Accessibility limitation (must have a person or item present that is significant to the spirit being called; -20%). Now the cost is 4 points, the same as a Hard Skill. End result:

Séance (Per/Hard): Collect a symbolic connection to the spirit. After a minute of preparation, Concentrate to call out to the spirit. The spirit will hear your call, and can choose to come to you. If it does, then for as long as you Concentrate, you can see and converse with it.

Following are the Limitation amounts required to convert various Advantages into Skills.

• A 5-point Advantage requires -80% in Limitations to become an Easy Skill, -60% to become an Average Skill, and -20% to become a Hard Skill. You can take up to +60% in Enhancements and still qualify for Very Hard.
• A 10-point Advantage requires -80% in Limitations to becoma an Average Skill, -60% to become a Hard Skill, and -20% to become a Very Hard Skill.
• A 15-point Advantage requires -75% in Limitations to become a Hard Skill, and -50% to become a Very Hard Skill.
• A 20-point Advantage requires -80% in Limitations to become a Hard Skill, and -60% to become a Very Hard Skill.
• A 25-point Advantage requires -70% in Limitations to become a Very Hard Skill.
• A 30-point Advantage requires -75% in Limitations to become a Very Hard Skill.
• A 35-point Advantage requires -77% in Limitations to become a Very Hard Skill.
• A 40-point Advantage requires -80% in Limitations to become a Very Hard Skill.
• Larger Advantages cannot be made into Skills.

Remember that unless the Advantage already requires an Attribute roll to use, you probably already have 5% to 10% of that amount covered. Noncombat "super-Skills" can usually get further cost breaks from Preparation Required and Requires Concentration; and unless the Skill already has something built into it that keeps it from being left "on" all the time, some sort of duration limiter should be applied.

When considering super-skills that fit the theme of a power source, you should be able to apply the appropriate Power Modifier as well: the above "Séance" skill could potentially take a Spirit Power Modifier, possibly bringing it closer to being an Average Skill (depending on whether or not the Spirit Power Modifier replaces any of the other Limitations).

Finally, the article that inspired this included a bit about paying for an Unusual Training Perk and narrowing the scope of the skill a bit. If we're truly reverse-engineering said article, the "target costs" for our skills would be 2, 3, 5, and 9 points for Easy, Average, Hard, and Very Hard, respectively, and every Limitation requirement would be at least partially offset by an unspecified Accessibility Limitation corresponding to whatever conditions Unusual Training might impose (unspecified because once we meet the above requirements, we'd drop the Unusual Training perk and its conditions; so it doesn't matter to the skill writeup what it is). Per the guidelines for Accessibility, I'd say that said limitation is good for -30%. If this logic makes sense, then the breakpoints change considerably:

5 points: -30% for Easy; -10% for Average
10 points: -50% for Easy; -40% for Average; -20% for Hard
15 points: -50% for Average; -36% for Hard; -10% for Very Hard
20 points: -45% for Hard; -30% for Very Hard
25 points: -50% for Hard; -34% for Very Hard
30 points: -40% for Very Hard
35 points: -44% for Very Hard
40 points: -48% for Very Hard
45 points: -50% for Very Hard

The above amounts incorporate the aforementioned -30% Accessibility Limitation. I also ditched any options based on positive modifiers, on the theory that building Enhancements into super-skills should probably be discouraged. (With exceptions, of course: the Turning Enhancement for True Faith is especially appropriate when turning it into a super-skill.)

EDIT: Note that if you use this second approach, the resulting super-skill should have some sort of "enabler Advantage" as a prerequisite, such as Magery or Trained By a Master. IMHO, this ought to be true of super-skills.

Thoughts?

Re: From Abilities to Skills
 

You should have submitted it to Pyramid is my seciond thought :)
You can have higher point advantages if you go for a lower skill roll.
Use the rules from Powers and examined in Psionics to determine the value.

Re: From Abilities to Skills
 

This is extremely interesting. It could make things a bit cheaper when an ability is needed mainly to provide flavour for a character concept, but won't see much use in play. Medium is a prime example for that actually.

Now I find myself compelled to buy even more Pyramid issues to have a look at the Kromm article. Dang. So much to read, so little money.

Re: From Abilities to Skills
 

This is a great write-up, although I stopped understanding the math when you got to Unusual Training. Possibly because I haven't read that Pyramid article.

Re: From Abilities to Skills
 

It strikes me that this could be the basis for a new skill-based magic system. One that could escape the commonly heard criticisms that default GURPS magic is not balanced with powers, and there is no spell building system.

For this, I would obviously use Magery as the enabling advantage. In my version, I would perhaps also select mundane skills as prerequisites for the "super skills" that are now essentially magic spells. But that's just because I personally like the idea of magic being a result of extreme mastery and knowledge of a subject.

An interesting analog for reducing fatigue costs for greater skill, would be to have different versions of the same "spell" skills. Easier ones with the "costs fatigue" limitation, and harder ones without. Then have a default between the skills, so that if you know the fatiguing spell, you can attempt the non-fatiguing one, but with a default penalty.

Re: From Abilities to Skills
 

Which is really the only problem I see here. It amounts to making Unreliable -3 (1 point instead of 8 in a VH skill) a -88% limitation that is always multiplicative, and can stack on top of an already maximally limited ability. The possibility of a 40 point ability that works even unreliably under pretty limited conditions for 1 point looks like munchkin-bait to me.

I think maybe writing a hard requirement for a fatigue (or HT, or character point or maybe even monetary) cost would make me more comfortable with the possibility of Average, Hard or Very Hard skills being taken at 1 point. It makes them rather spell-like, and while advantage granting spells aren't terrifically well balanced against raw advantages, that costing something to use limit does a decent job of keeping them under control.

Re: From Abilities to Skills
 

Ignore that part; it's broken.

True; although I personally have my reservations about doing so, as limiting yourself to what this setup says is possible potentially hamstrings your design options.

Note that, aside from the bit about the "enabling Advantage", nothing is said about prerequisites in this; nor is anything said about defaults. These are the two "controls" on Skills that don't have Modifier counterparts, even in theory: Magic uses the former (in the form of prerequisite trees) to limit access to unusually powerful spells, and the latter can possibly be used in cases where the skill in question is deemed as being too expensive for what it does, providing a way to pick it up for free.

Granted, there's little precedent for the latter approach; and with good reason. The only example of supernatural skills with defaults exists in the Ritual Magic variant.

Thaumatology has an option in it for attaching Enhancements to skills by means of skill penalties and energy costs; such an option could possibly be generalized (e.g., removing an inherent limitation instead of adding an enhancement) and applied to this sort of thing; but it obviously wouldn't give you an end-run around energy costs. That brings me to:

Yeah; ISTR Kromm or PK mentioning somewhere that the energy costs of the likes of spells and imbuements are the primary mechanism for keeping them under control, and that ways to reduce or eliminate such costs shouldn't be introduced lightly if at all. So making "Costs Fatigue" or a more severe counterpart a mandatory part of the Limitation total probably wouldn't be out of line.

I'd also like to see people take this out for a test drive: build some skills with it, and show your work; try to find cases that just feel wrong (super-skills that do too much or too little, etc.) As a possible example of the latter, try turning "True Faith (Turning, +65%)" into a "Turn Monster" super-skill: I took a crack at it and ran into difficulties. For instance, to turn it into a Very Hard super-skill would require -115% worth of Limitations (-65% to offset the Enhancement, and another -50% because it's a 15-point Advantage), and can't include the usual "Requires (Attribute) Roll" Limitation (because the Turning Enhancement incorporates a Quick Contest of Will into the mechanics).

Re: From Abilities to Skills
 

To continue with this exercise, it might be useful to calculate the limitation value on the "prep time vs skill penalty" mechanic that Power Blow and Breaking Blow have. I know PK has a calculation for some similar case, but I haven't seen one for this.

Re: From Abilities to Skills
 

If I'm not mistaken, this means that fireball at 9d max should have a minimum cost of 9 as a skill and (even after fudging a bit) should be a VH skill yes?

That said, having to buy magery (a talent with 3 level maximum and detect built in) isn't any more limiting than such a requirement on a power. Numerous other spells are easier than they should be, and the underlying advantages usually cost way kore than 45 points.

Yet another reason standard magic is a load.

Re: From Abilities to Skills
 

To be fair, advantages in GURPS, AFAICT, are not priced for utility, but for 'how impossible it seems' and 'how common the game and/or setting designer wants it to be.'