Suggestions for Pricing of Limitations

[Nedorus]

I'm using this post as an inspiration / basis for a summoning ability to mimic that of a well know cyberpunk game (where you shouldn't trust elves or cut deals with dragons).

I'll either use Super-Memorization, Cosmic-Power or the pricing suggested in Powers p. 63 as a basis for pricing. Then adding in:
Limited (Summonable Spirits of your Tradition) -50%
Costs Fatigue 1 -5%
Magical -10%
Requires Attribute Roll (QN), resisted by Will -20%
Maybe some levels of "Reduced Time" depending on the cost basis I decide to use (I want the spirit allies to be reasonably summonable within a single combat)

Now to my question:
I want to factor in two more limitations:
Limited Time: a summoned spirit only sticks around for a limited time; it will return to its home plane when the sun rises or sets
Number of Services: a summoned spirit will return to its home plane when the through with all of the services it owes

These are intended to be "whatever happens first" limits.

The number of services will most likely end up to be the margin of victory (or margin of success) from the actual summoning (Quick Contest of QN and Will)

I'm looking for suggestions on how to price these limitations.

P.S: is there an easy way in the rules to make the FP cost depend on the summoning roll as well? Something like "costs X - Margin of Success"?


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Building the Ability
Here I will update the ability that I'm building for others to reference quickly without reading through the entire thread. I will change but I'll try to always reflect the
latest changes.

Summon Spirit
You summon a spirit of your tradition as a temporary ally. This takes 1.25sec (round up) per 10 CP of the ally summoned. Roll a quick contest of your QN (plus Summoning Talent) vs. the spirits Will. Whether successful or not you loose QP equal to the margin of success of the spirit. The spirit own you a number of services equal to your margin of victory. However the Spirit will only serve you until the next sunset or sunrise and will return to its home plane when all services are used up or the time is up (whichever comes first)

Statistics:
Modular Abilities (Super-Memorization) (Magical -10%; Requires (QN) Roll (resisted by Will) -20%; Social Only +0%; Costs QP (margin based) -15%; Trait-Limited (Summonable Spirits of your Tradition) -50%; Reduces Time 3 +60%)

Cost:
- 23CP for 25%-Starting-Point-Spirit
- 43CP for 50%-Starting-Point-Spirit
- 62CP for 75%-Starting-Point-Spirit
- 101CP for 100%-Starting-Point-Spirit

Interestingly I noticed that the cost doesn't really change much when I change the type of modular ability. +/- 3 points at the low end and +/- 10 at the high end...

[Anaraxes]

Originally Posted by Nedorus

P.S: is there an easy way in the rules to make the FP cost depend on the summoning roll as well? Something like "costs X - Margin of Success"?

The glib answer: Alter the value of the Costs FP Limitation by the expected value of the summoning roll. It's a bit harder to calculate that in practice, since the outcome depends on the summoning skill level and target difficulty mods.

If you can expect to beat your skill by 2 on the average cast, for example, then two levels of Costs FP will actually not cost you anything in the average case -- or about half the time if your tasks are appropriate to your skill (TDMs that give you an effective skill of 10, so -2 to say -6 for "normal" professional levels). Rolling higher than your skill means you simply fail.

I'd suggest charging the full FP cost in case of failure. (You just know someone's going to argue that failure to activate means they shouldn't get charged anything since nothing happened...) But the point of Costs FP is to limit the amount that you can use the ability, and "happens only on a tie" is so rare I wouldn't bother to do the math and just round to -0%. I'd also suggest using the Rule of 16 for the purposes of calculating the FP cost. That is, the effective skill can be no higher than 16 when comparing it to the die roll to see how many levels of FP you save. (You might or might not use that rule for the actual success, but the math is easier when there's a cap on how high the skill can be, and it means that the "crit fail" always costs FP.)

So, scribbling a little chart, making some assumptions, and rounding off, I get that on average, you'll pay about 25%-40% of the maximum FP cost for the spell. All the low rolls save you the full amount, depending on skill assumptions; it's only on the ones where you just make by a few that you pay FP to make up the difference.

So, use either 25% or 33% of the Limitation value for Costs FP (Margin-Based). Let's split the difference and call it 1.5% / level*. It's barely noticeable at skill 16, and not even half value at skill 12 -- and you know the players are going to be pumping those skills up on their characters so they can use them freely. If you want to be generous, make it half value (2.5%/level) but make sure that summoning has enough difficulty mods built in to balance high skills. (More powerful creatures cost more, so maybe it's likely free to summon a tiny sprite that's just a glowing dot that doesn't even light a room, while calling the unicorn mount or pit fiend is not only likely to fail, it's going to cost you even on the crit success.)

While we're on the topic, I should note that "Margin-Based" appears in the rules a few times with different meanings. There's the "triple cost" version for Afflictions of levelled traits. And there's the 0% Feature version that shows up in RPM, though that's energy costs and not CP costs. So, I'm just adding to the confusion by using that name as an adjective for this modifier.

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* Using the RAW value of Costs FP at -5% / level. I'm in the camp that thinks the first couple of levels are worth a little more, because there's a big difference in limiting use between 0 FP and 1 FP, while bigger FP costs generally only appear on characters that have a big Energy Reserve, knowing they've got all those abilities to power. See past threads for lots of discussion on that topic.

[Nedorus]

WoW! That's a lot to take in. Thank you so much Anaraxes! I'll need some time to dissect this piece by piece... But I'm pretty sure my solution will be based on these suggestions.

I'd suggest charging the full FP cost in case of failure.

This I intend to do. Failure and Critical Failure need to be addressed and I want to make this rather tough.

I'd also suggest using the Rule of 16 for the purposes of calculating the FP cost

This is an excellent suggestion. I'm designing the whole summoning (banishing and binding as well) thing as a Power and thus with a talent and based on "the fifth attribute" QN. So high skill levels are quite possible for specialized characters. I would want at least SOME FP cost (I'm using QN so it'll actually be QP but this doesn't matter for this discussion)

More powerful creatures cost more, so maybe it's likely free to summon a tiny sprite that's just a glowing dot that doesn't even light a room, while calling the unicorn mount or pit fiend is not only likely to fail, it's going to cost you even on the crit success

Those aren't exactly the kind of spirits available but yes, that is the intention. The beginner summoner will be challenged and drained by even the smallest sprites while the specialised expert will conjure these up without breaking a sweat only struggling with the real biggies...

I'm actually thinking of allowing "extra effort" styled approaches here as well.

Thanks again for the input. Great things to consider!


... now to my main question...

[Nedorus]

P.S.: I was just re-reading the psionic powers version of "margin-based". This makes the effect based on the subject's margin of failure.

I think this is VERY close to what I want.

I could make the FP-cost depend on the subject's margin of success (not victory!). Just to spell this out a bit more explicitly (and make my decision transparent for others who may want to do something similar), I'll list out the odds for a 50CP Animal Spirit and a 250CP Water Elemental

50 CP Animal Spirit
Will 11
FP Cost - Chance
0 FP 50%
1-2 FP 24.1%
3-4 FP 16.5%
5-6 FP 7.4%
Crit: making the summoning automatically fail (?) and costing 7-8 FP has a chance of 2%
The "expected" FP cost being about 1-2

250CP Water Elemental
Will 14
FP Cost - Chance
0 FP 9.3%
1-2 FP 21.3%
3-4 FP 25%
5-6 FP 21.3%
7-8 FP 11.5%
Crit costs 10-11FP and again has a chance of 2%
The "expected" FP cost being about 4-5

This sounds very reasonable to me...

Psionic Powers prices the enhancement as described there at "triple cost". Using the same "factor" for the changed "costs fatigue" limitation would result in an equivalence of "cost fatigue 3" and "cost fatigue (margin based)" as the same. When looking at the above numbers this feels roughly OK.

So I'll add the following limitation:

Originally Posted by House Rule

Costs Fatigue (margin based) -15%; pay fatigue points equal to your opponents margin of success on his resistance roll.

P.S.: I think there is no longer a rule in 4th edition that a crit in a quick contest does anything special, right?

[Anaraxes]

I think the two methods work out about the same for typical ranges of skill. The triple-cost version was originally for positive Enhancements (stacking levelled Advantages via Affliction). But I suppose it's really a way of saying "you'll probably succeed by about three on average". So that's a reasonable shortcut to the process I described. Six levels of Costs FP, halved, is -15%. And it's certainly a lot easier to just say "it's -15%" than to fiddle with the math or worry about the difference between "max 4 FP" and "max 6 FP".

(The point of the math I went through is in my mind just thought process to work out some reasonable value and have some confidence in it. The other main resource is of course just comparing to existing traits. Limitation values aren't really probabilities, so there's no point in getting too strict about them.)

I think there is no longer a rule in 4th edition that a crit in a quick contest does anything special, right?

The Contests section doesn't mention any effect, so short answer: Nope.

Campaigns does call the roll for a Contest a "success roll", which strictly speaking means there are crit successes and failures. But in the absence of any specific guidance for the Contest rule, that at best winds up in the "GM decides on something good/bad" section of the crit rule.

Crits on success rolls are automatic success/failure (by the most basic definition). Mostly that'll be a moot point, as someone that rolls a 3 probably has a better MoS than someone that rolled a 7, unless there's a big difference in their skills. But if you want crits to have some meaning in Quick Contests*, then I'll suggest the "GM decides" clause could be

• Crit success always beats normal success, regardless of MoS
• If both rolls are crit success, nobody wins. (A "push", like tied successes.)
• Crit fail always loses even to normal failure, regardless of MoS. (MoF?)
• If both rolls are crit failures, nobody wins. If the situation allows, terminate the Contest with no conclusion. (The contestants get forcibly separated by the environment, the server/network/power goes down to kick them out of the OASIS, whatever.)

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* whether because crits are just fun, because you want there to be some chance the grossly outmatched underdog can freakishly win despite a difference of 5, 8, 10+ skill points, or more mechanically because you might be using rules like Luck, Destiny / Hero Points, or Buying Successes, where they might come up in an important Contest by player choice.

[Nedorus]

Originally Posted by Anaraxes

• Crit success always beats normal success, regardless of MoS
• If both rolls are crit success, nobody wins. (A "push", like tied successes.)
• Crit fail always loses even to normal failure, regardless of MoS. (MoF?)
• If both rolls are crit failures, nobody wins. If the situation allows, terminate the Contest with no conclusion. (The contestants get forcibly separated by the environment, the server/network/power goes down to kick them out of the OASIS, whatever.)

I think this is pretty much how I've handled in the past as a "house rule" ... I think I'll stick to that because ... you listed all the reason I need already hahahaha ... FUN