How can I load polyhedral dice so they roll poorly?

Question

My current GMing situation mandates I roll dice out in the open. However, I want some special loaded dice that'll roll poorly in case I need to save a PC or the plot. There are some caveats:

1. Close inspection can't reveal that the dice have been altered.
2. The balance shift should be just enough to make the roll appear to be bad luck.
3. I need to use a full standard polyhedral dice set (d4 through d20).

How can I load dice so that I have a set of GM-only bad luck dice?

Note that I am uninterested in alternatives to loaded dice. I can't change this house rule so I can roll behind a screen. I can't introduce a plenthora of extra house rules and I also can't, for example, just lie and claim secret modifiers are altering these out-in-the-open rolls. In other words: this is not How can I fudge die rolls when they're made out in the open?

Answer 1

(I'd like to offer a frame challenge. I believe your real question is not "how can I cheat at dice?" but rather "how can I avoid accidentally killing PCs with good rolls?".)

Your host has asked that you not cheat at die rolls, and it's best to honor that request.

Your root goal is to shield your players from the effects of bad DM dice rolls, and there are lots of ways to do that that don't involve being deceptive about dice rolls.

In past 3.5e games, I've worried about characters occasionally being killed in one hit by critical strikes (or simply by high-damage strikes against characters with low hit points). I solved this by telling the players there was a house rule: even if you drop below -10 hit points, you can still be saved if someone heals you very quickly.

Another solution is just to tell the players that you have a house rule that NPCs cannot score critical hits.

Another popular house rule is to allow some sort of "action points" such as Eberron uses: give the players some resource they can spend to keep their characters alive when the dice act against them.

But, if you find yourself in trouble even after all these things, remember that you can adjust monster statistics on-the-fly. I saw someone write recently: "facts about the world are in your head; they are not real until you tell them to the players, and you can modify them until that point". Monster hit points, monster attack bonuses, monster damage levels, and availability of reinforcements are all things that you can change on-the-fly to adjust the combat difficulty, without needing to lie about dice rolls.

Answer 2

Three Suggestions:

First, if you are like most DMs I know, you probably own a fistful of any given kind of die. You can do something called a chi-square test to determine which die were manufactured imperfectly (hint: all of them) and might favor particular numbers. I would expect the odds to be slight, but perhaps an off-brand may be more unfair, one way or the other. An advantage to this approach is you don't need to introduce any new dice; you just favor one or another that you already own.

Second, you could try to find some weighted dice online. A quick search turned up some possibilities, but I haven't tried any of them so I can't back up any advertising with personal experience.

Third, many games provide circumstantial bonuses/penalties you can apply to a die roll to artificially, but legally, impact the odds.

An observation

Sometimes, the only winning move is not to play roll. As the GM in any game that has one, you have great control over what does and doesn't happen. If you know the wizard is at low health, perhaps the baddie simply attacks someone else, attempts a parley, regroups, runs away, or does something other than directly attacking the wizard. This technique can produce interesting story results, but be difficult to execute in a believable way. However, you are a participant in a partially luck-based game. Every time you reach for the dice, you should be prepared to accept anything they may show.

Answer 3

I will refrain from making any moral judgement if loaded dice are good or bad. Therefore, I will just answer the question as it is presented.

Depending on the dice, you can decrease the odds it will tumble out of a "good" number slightly if you sand and smooth the edges of the opposite side.

So for a d20, if you make the edges around the 1 (usually opposed to the 20) rounder, chances are it won't stay on the 1, as the energy required to make it tumble towards one of the adjacent numbers is lower. This doesn't mean it will never roll 20, but it is way harder for it to stop on the smoothened edges face.

You can test how much it is wobbling by buying two identical dice. Smooth the edges on one, and put both standing with the 20 up. now give a gentle nudge on them (try to make the same force on both) and you will see that the one with the sanded edges will topple out of 20 easier.

If you get a non-glossy dice, the smoothened edges are really hard to see. Since you have two of the same kind, you can swap and hide the loaded dice.

The trick is to get a dice made of a material that can be polished to better hide the rounder edges. Transparent dice, and glossy dice are the worst. Low quality dice are better for this.

Answer 4

First of all;

Do not cheat!

Even if it is to let your PC's live, cheating takes the agency and fun out of the game. It is no different than cheating towards TPK

And even if you use loaded dice, you just reduce the probability of some rolls. Not eliminate them. And the more heavily biased a die is, the harder it is to conceal the bias. You will still end up killing your PC's. Just not as frequently.

How to avoid killing PC's

There are two things that determine the probability of character death.

1. The setting determines how likely it is for the PC's to encounter deadly situations. Is it a post-apocalyptic wasteland where radiation, deadly bio-plagues and mutated monsters lurk around every corner or is it the victorian era pastoral countryside where the biggest threat is tuberculosis, falling off a horseback or a romantic heartbreak.
2. The system determines what the dice rolls correspond to. Is it enough to roll a 10 in a d10 to behead your opponent or do you need to go through a series of attack, defense, resistance and survival checks to actually do any lasting harm? Does rolling a critical have to mean that the opponent has to die, or is being defeated just means that you are somehow unable to fight but not necessarily dead?

The trick is, as the GM, both of these factors are within your jurisdiction to modify as you see fit, as long as you are clear and consistent about it.

Is your murderous setting killing your PC's? Make their opponents just as vicious but less murderous. Maybe the giant spiders would rather keep their victims alive, so they can eat them later.

Does your deadly combat system get your characters on every natural 20? Just add an easy survival check that they have to fail in order to actually die. Otherwise they live but are still injured badly.

One last advice: Even if you reduce the threat of character death, never eliminate it completely, and when the dice roll that way despite the odds, do not fudge it. Failing at this may push your characters to become murderous cretins.