1134318_13908364_smFor a long time, I’ve been dissatisfied with the way some games handle wild, improbable, luck.

D&D, for example, has no luck mechanism per se; only the critical hits subsystem comes close, where if you roll well enough, you score multiple damage, and in the skills subsection, whereby rolling a 20 on a skill check permits a success even if the raw total is not theoretically enough.

This is especially true of my Shards Of Divinity campaign, where a house rule disposes of the latter ruling in favour of an “it takes longer” approach. This is, in reality, just a shorthand version of the published rules, since it only applies when multiple attempts at the skill check are permitted; eventually, the character will roll a success under the normal rules, this merely replaces all the necessary die rolling with a time frame.

I wanted a mechanism in which luck could behave as luck is reputed to behave – it should give an edge or an advantage, but should not dominate results, and it should be fickle. But for a very long time, inspiration has been in short supply.

The Origins Of The Concept

Recently, though, an idea came to me – while watching, of all things, a TV documentary on Mandelbrot and the rise of Chaos as a mathematical and physical principle. The key to Mandelbrot’s mathematical functions, and to chaos mathematics in general, is the concept of iterative functions, something that had fascinated me ever since I had read that an iterative function had been developed that output decimal places of pi – if you fed in the first N digits, you got another N digits out, feed those in and you got the next N digits and so on.

The idea occurred to me that using the results of some sort of luck roll not only to determine how much luck a character had a given time, but also the scale of the next luck roll, would inherantly act to keep luck points from piling up until they became some overwhelming monster that totally dominated play.

Seventh Sea uses a similar idea, and part of the inspiration came from that source as well. In Seventh Sea, there is only one pool of a luck ‘equivalent’; The GM has an unlimited supply, but each time he uses one, he has to give one to the players. Unused luck generates additional XP, in other words the stroke of luck is that the characters learned more than they normally would from a series of encounters.

The value of Luck

So, what did I want characters to be able to do with a luck point? What was a luck point going to represent?

Champions uses a system whereby you roll however many dice of luck you have bought for your character, and count the number of sixes; each 6 represents an escelation of luck, from minor advantage to minor miracles. The normal Hero system restricts characters to three dice of luck, and I could not see why that was the case; I thought that characters who were willing and able to pay for the privilige should be able to buy more, to better their chances of getting at least one point of luck on a regular basis. Many years ago, when first considering this, I calculated that 14 such dice represented a critical threshold, where the chance of a miracle (3 points of luck) was higher than the chance of only getting a minor advantage. To avoid Deux Ex Machinas at every turn, I employed the simple tactic of capping the number of dice that could be bought at 13. Over the years, the interpretation of luck points has evolved, so that allies found that an exceptionally lucky character was lucky for them to have around, and we’ve since found the luck mechanism to be a useful metagame shorthand for all sorts of powers that were otherwise quite difficult to interpret into game mechanics.

I didn’t want luck in D&D to be anywhere near this powerful; my intention was that it be something that everyone had, in varying degrees, and that gave an advantage that had to be employed tactically. I wanted it to give the players more options, and the NPC opposition more options.

The ability to change the results of a die roll by one step sounded about right at first – so that a character who rolled a ’19′ in battle could use a luck point to change the result to a ’20′. A character who just missed a skill roll that they would normally succeed on could do the same thing. A character who was being mauled by the opposition could use a luck point to reduce the enemy’s attack roll and get some breathing space. And, of course, two could play at that game; if I had underestimated the effectiveness of an important encounter, I could give them a tactical advantage to make up the difference, and make the encounter more thrilling and suspenseful – at the expense of giving the PCs more experience when they eventually won.

But, when I looked at the luck generation system I had come up with, it potentially gave away too many luck points for that. So I settled on a five-point scale for certain specialised meanings:

  • changing a critical failure into a simple failure costs 5 luck points;
  • changing a failure into a success costs the difference in luck points;
  • changing a success into a critical success costs 5 luck points;
  • increasing the critical multiplier of a weapon for one attack only costs 5 luck points for each step;
  • increasing the damage rolled by an attack by one point, up to the maximum that can be rolled, costs one point of luck;
  • changing a failure into a critical failure costs 5 luck points;
  • changing a success into a failure costs the difference in luck points;
  • changing a critical success into a normal success costs 5 luck points;
  • decreasing the critical multiplier of a weapon for one attack only costs 5 luck points for each step;
  • decreasing the damage rolled by an attack by one point, to the minimum that can be rolled, costs one point of luck;
  • an extra 5′ step of movement costs 5 luck points;
  • an extra dice of luck (to a maximum total of 10 dice) for the next game session costs 10 points.

This would mean that a lucky character would be more likely to blindly pick the right answer, be in exactly the right place to make the difference in battle, be more likely to come through failures and mistakes unscathed, and so on, but their capacity for doing so would be limited.

Rolling Luck

At the start of each session of play, each PC rolls the specified number of luck dice. The first time the system is used, the character rolls d10-1 for the number of dice of luck they have from “last time”.

The total rolled, Ignoring the 10s place, is the base number of dice of luck for next session.

The total rolled is also the number of points of luck the charater has available for use in this game session.

Characters must decide immediatly whether or not to expend any of these luck points for additional dice of luck next session.

The GM supervises these rolls for each character and notes the number of dice each character has coming to them next time. The players should also note this number for redundancy.

Analysis Of The Luck Rolling System

Characters can end up with anywhere from 0 to 10 dice of luck for a session. That gives them anywhere from 0 to 60 points of luck to use.

Because the total is a random value on a probability curve, characters can predict within rough guidelines how many points of luck they will have next session, enabling an informed decision as to how many dice of luck to buy.

The more dice of luck you have, the closer the result will probably be to the average of 3.5 per die, but there is always a strong element of chance, because the more stable tens place is ignored. This means that the more dice of luck you have at the start of a session, the more secure you can be that you will have a reasonable amount of luck points next session. However, the more dice you have at the start of a session, the more variable the number of luck dice that you will have available for next session becomes.

There is NEVER a good excuse for not having at least one dice of luck next session. If a character rolls a luck point total that ends in a zero, they will have at least 10 points of luck, permitting them to buy at least one dice for next time – at the expense of having no luck this session.

Players can use their luck points at any time, for any roll that they make. They can also use their luck points at any time, for any roll that the GM makes. Each time that they do, the GM should reduce the XP awarded for the encounter by 10 per PC.

Side note: I thought about basing the number of dice of luck on the amount of unused luck this session, but quickly realised that it enabled players to manipulate the system too readily so that they always had a high number of dice of luck, simply by controlling their expenditure of luck in a session. This would have ensured that they always had an edge when they needed it, which runs contrary to the objective of these rules.

Unused Luck

Luck does not accumulate. At the end of a session, unused luck is redeemed by the GM at a rate of 10xp per point unused.

With a maximum of 60 points of luck, a character can potentially gain as much as 600xp from unused luck in a game session, but this is unlikely to occur. A more likely value is 180-360 xp, which is a reasonable amount that doesn’t overwhelm the game system.

GM use of Luck

The GM has an unlimited amount of luck to draw on. However, he starts with exactly the same amount that the characters have AFTER they have bought additional dice of luck for next session. Every point of luck that he uses beyond that limit awards EACH PC 10 additional xp at the end of the encounter, so most uses of luck will cost him an extra 50xp at least.

Furthermore, every 6xN points of luck (where N is the number of PCs) that he uses beyond this limit also gives characters an extra dice of luck for the next session, even if this violates the 10-dice maximum that normally applies. Characters can never start with more than 60 points of luck, but if the DM gives the players too many dice to draw on, achieving that 60 becomes more likely. It also increases the likelyhood that the PCs will have unused luck next session, in effect giving the players a double advantage.

Since PCs with zero luck in a session also reduce the number of luck points that the GM has to draw on, it becomes more likely that he will need to award extra dice of luck, so getting that character off the zero mark for next session.

Note that the GM has to use his luck reserves for ALL characters that he controls, both enemies and NPCs allied to the party. He should use Luck as a tool to enhance his storytelling, ramping up the usage by the opposition when the PCs get close to a significant victory so that they, in turn, have a lot of luck points available for the ultimate encounter.

Lucky – The Feat

A character can also take the Feat “Lucky”, which gives the character a minimum of 1 dice of luck at all times. This does not add to the number of dice of luck the character can have, it simply increases the minimum. This feat can be taken multiple times, but no more than five times is permitted.

Luck Wars

It should be obvious that with both PCs and GM having the same total luck points to draw on in a session, luck points can be used to cancel each other out, and some players may opt to do so. This is ultimately shortsighted; better to husband your luck points for the moments that really matter and make a difference to the character.

In general, it should be considered bad form for luck to travel both ways on a single roll; it’s far more satisfying to let luck ebb and flow, letting the GM get the players into tight spots and then using luck to ensure that the PCs can battle their way out.

To enforce this behaviour, if a PC uses luck to counter the GM’s use of luck, the luck that the GM had allocated to the action returns to the GM’s pool, unused, while the PCs luck is expended. Instead of using a luck point to counter the GM’s luck, the players expend their luck to block the GM form using his luck on that attack or roll.

Similarly, if the GM uses his luck to block a PC usage of luck, the luck points are returned to the PC for use later, while the GM’s are expended on the roll, in the manner specified, as though the Player had not used luck at all. The result is that the PCs can force the GM to use up his luck – at the price of the GM being more effective in the short term – be it inflicting more damage, hitting when he otherwise would not, or whatever.

Consequences & Ramifications

In effect, the more players rely on “forced luck” to achieve their results, the less XP they earn for the day; the more GMs rely on “forced luck” to make the PCs lives more difficult, the more XP the players get.

In any given session, neither side of the screen gains an advantage, but the use of luck should enhance the dramatic tension of an encounter or battle as fate swings to the advantage of first one side and then the other. It should permit the GM to enhance the play within his campaign, making it more spectacular and thrilling.

That’s the goal – now to see if it works in play…

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