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How to make a device to randomly choose one of three possibilities, with caveat that sometimes one of them is not available?

In general, a deck of cards is useful to select a choice from a menu that excludes prior choices. In this particular case, choose three playing cards to represent the monster's possible actions. On ...
sptrashcan's user avatar
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45 votes

How to make a device to randomly choose one of three possibilities, with caveat that sometimes one of them is not available?

Use a d6 with a reference table In the following table, the main entry is the attack assuming the monster is free to choose from among all its attacks. The parenthetical entry is the attack used only ...
Kirt's user avatar
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21 votes

How to make a device to randomly choose one of three possibilities, with caveat that sometimes one of them is not available?

This looks like a job for a Rondel. Put the three attacks in consecutive sectors of a circle, and after the initial d3, put a marker (a coin, a d6, whatever) on the previously used move. When choosing ...
Bass's user avatar
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17 votes

Benefits of PC attribute generation methods? (custom RPG)

What is your Goal? Determining "best" requires a defined metric to judge "best". You have to have a known goal to find the best fit for that goal. What goal is your stat generation ...
ValhallaGH's user avatar
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16 votes
Accepted

How can I simulate decreasing randomness even though randomness is increasing?

Sort of. As the number of dice increases, the range of potential outcomes increases. As the number of dice increases, the likelihood of an extreme outcome decreases. To show this, let's assume a WIN ...
fectin's user avatar
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11 votes

Benefits of PC attribute generation methods? (custom RPG)

Let's take a quick look at several generation methods, and how they are employed, before we discuss how each of them impacts the character generation. I speak from more than a decade of experience ...
Trish's user avatar
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11 votes

How does this 2D6 probability math make sense?

If you are rolling two six sided dice, there are 36 different combinations of faces that can come up. If several of the faces have the same symbols, many of those combinations will have the same ...
Blckknght's user avatar
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10 votes

How to make a device to randomly choose one of three possibilities, with caveat that sometimes one of them is not available?

Using a Standard d6 and Coin A quick-and-dirty way to approach this is to use a bog-standard d6 to determine the first attack, any ol' fair coin to determine each subsequent attack, and a grid of ...
Xander Henderson's user avatar
9 votes

How does this 2D6 probability math make sense?

The really Easy Way To Understand This Is With A Table For small numbers of dice, it's often possible to just exhaustively list out all the possibilities, and organize them into a table. I've done ...
Novak's user avatar
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9 votes

Do you know the angles of a face for a 7 or 14 sided die?

d14 According to this MathExchange answer, the faces of any such trapezohedron will have two 90-degree angles opposite from each other. The angle \$\theta\$ at the pole vertex is given by $$ \tan \...
HighDiceRoller's user avatar
9 votes
Accepted

How to calculate advantage/disadvantage with multiple dice (e.g. 3d6, 2d10, etc.)

Multiset enumeration For the most part, AnyDice operates by enumerating all possible multisets that could come out of a pool of dice. For \$n\$ dice of \$y\$ sides each, the number of possible ...
HighDiceRoller's user avatar
8 votes

A deck of poker cards as dice

Roll20 has a feature just for that You can use the Cards feature on Roll20. As per the documentation: Card Decks in Roll20 are Collections (e.g. a deck) of one or more card objects that can be ...
Nobody the Hobgoblin's user avatar
8 votes

How does a low-accuracy, high-damage action work in World of Darkness's dice system?

Instructions unclear, Ate the Dice? You seem to have a disconnect between how you interpret the mechanics of Storyteller system Combat and how it actually plays out. Let me start with the original d10 ...
Trish's user avatar
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7 votes

Discord DiceParser (By RoliSteam/KDE?): ceil() function syntax needed (need to "round up" an average)

For positive integers you can use a floor-division (which most programming languages, including DiceParser, use for division of positive integers) to implement a ceiling-division using the following ...
HighDiceRoller's user avatar
7 votes

Probability help on rolling two D4 with all doubles counting as zero except double 4s, which count as 4

The probabilities are right, but beware of approximations. You got the right probabilities in terms of fractions, but when you approximated them with percentages you get a sum of 101%. You are adding ...
Eddymage's user avatar
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7 votes

How to make a device to randomly choose one of three possibilities, with caveat that sometimes one of them is not available?

You could make (lego, 3d print etc) a D6 and two hemispheres that can attach to any face. Now when you need to restrict an attack, you can attach the two hemispheres to the 2 sides corresponding to ...
Sam Dean's user avatar
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6 votes

How can I simulate decreasing randomness even though randomness is increasing?

Dice pools are actually excellent at producing the sorts of results you seem to want. Extreme results are possible but increasingly unlikely. Here is something to help you out with your math... https:/...
guildsbounty's user avatar
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6 votes

Benefits of PC attribute generation methods? (custom RPG)

The two basic methods for generating stats are: Deterministic With deterministic methods, you calculate. You have fixed values, or points or categories whatever it is. There is no uncertainty involved,...
nvoigt's user avatar
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5 votes

How does this 2D6 probability math make sense?

First, "percent" means "per one hundred", right? So we're dealing with hundreds. 50% is just another way of writing 0.5, or 1/2. Half of the outcomes (1/2, 0.5 or 50%) on one roll ...
From's user avatar
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5 votes

How to calculate advantage/disadvantage with multiple dice (e.g. 3d6, 2d10, etc.)

Combinatorics Various methods are available depending on how accurate you want to be and the sample space size. For fistfuls of dice, you can brute-force count them: manually, with a spreadsheet, or ...
Dale M's user avatar
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5 votes

How does a low-accuracy, high-damage action work in World of Darkness's dice system?

What you're looking for is Storypath. If you're thinking of a system that uses die pools that's similar to the one used in World of Darkness in which a roll that's hard to pull off adds extra effect ...
Jadasc's user avatar
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4 votes

How to make a device to randomly choose one of three possibilities, with caveat that sometimes one of them is not available?

Use cards instead All you need is three cards, one for each attack. Each round you pick one card to determine what happens. All you need to do to take out the tail attack is put that card aside until ...
Jack Aidley's user avatar
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4 votes

How does a low-accuracy, high-damage action work in World of Darkness's dice system?

Here is my current idea if anyone could give their appreciation: define the dice pool as conventional dice pool definition subtracted by an extra layer of difficulty (eg. -2); then, if the player ...
Draconis's user avatar
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3 votes

How can I simulate decreasing randomness even though randomness is increasing?

As the other answers have explained, yes, the more dice you roll, the more possible different outcomes you can get. As you are only counting successes, the more dice, the more possible successes. ...
Nobody the Hobgoblin's user avatar
3 votes

How to make a device to randomly choose one of three possibilities, with caveat that sometimes one of them is not available?

Use a coin. Beyond the first roll, you're just rolling a d2 and picking one of the options that weren't used before. If you can 3D print, make a coin with one side "1", and the other side &...
T. Sar's user avatar
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2 votes

Using AnyDice.com to calculate Non traditional dice combinations

Thanks everyone for the answers and input. For redundancy to get an answer I did ask the creator of Anydice.com. He in fact wrote back and gave this answer. Its just amazing. ...
Keith Plunske's user avatar
2 votes

Are there any role-playing games which use dice larger than a d100?

MAID Rpg: d216 by technicality. maid-rpg generally uses d6 and d66 (2 d6 with the order being relevant, consulting a table for results), but the items section uses ordered 3d6 to generate random items:...
Trish's user avatar
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2 votes
Accepted

How does the probability of success change by increasing the size of roll & keep dice pools or altering the difficulty number?

This is a quick look at numbers to give an overview of probability changes. I've used AnyDice program to calculate chance of success for a range of STAT and DC values, then plotted those on a line ...
tl.'s user avatar
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2 votes

Probability help on rolling two D4 with all doubles counting as zero except double 4s, which count as 4

Eddymage's answer is correct, but I thought I would provide a supplementary answer to introduce one of RPG.SE's favorite tools: AnyDice. (We even have a tag for it: anydice.) After wrestling with some ...
MJ713's user avatar
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2 votes

How to calculate advantage/disadvantage with multiple dice (e.g. 3d6, 2d10, etc.)

The Stand-Up Maths Youtube channel has done an interesting video on this subject. I've summarized the findings below. For rolling advantage with two N-sided dice, the probability distribution is ...
Adam's user avatar
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