Polyhedral dice
Polyhedral dice are, literally, dice with many sides. Though the term is normally used to refer to dice with sides other than six, technically the common six-sided die is also polyhedral. Polyhedral dice are popular in a wide variety of role playing games. The most common are in the shapes of the five Platonic solids.
Typically, these dice are referred to by the number of faces they have: a 'd6' is a regular cubic die, pronounced 'dee-six.'
Common Dice
| Type | Shape | Notes | Platonic |
|---|---|---|---|
| d4 | tetrahedron | Each face has three numbers: they are arranged such that the top number is the same on all three visible faces. | Yes |
| d6 | cube | A common die. Opposite faces must add to seven. | Yes |
| d8 | octahedron | Each face is triangular; looks something like two Egyptian pyramids attached at the base. | Yes |
| d10 | Irregular decahedron; see: 10-sided dice | Each face is kite-shaped; the smallest angle of five faces point to one edge, the smallest angle of the other points to the opposite. Not a regular polyhedron. Often, all odd number are on one half of the die and all even faces are on the other half. | No |
| d12 | dodecahedron | Each face is a regular pentagon. | Yes |
| d20 | icosahedron | Faces are equilateral triangles. Typically, opposite faces add to twenty-one. | Yes |
Uncommon Dice
| Type | Shape | Notes |
|---|---|---|
| d7 | A very uncommon die type, it's shaped as a pentagonal prism, thick enough to land either on its "edge" or "face". When landing on an edge, the topmost edge has pips for 1 through 5. The pentagonal faces are labeled with the digits 6 and 7. | |
| d30 | Each face is in the shape of a rhombus (diamond-shaped). | |
| d100 d% | Trade name: Zocchihedron | Usually modelled by rolling two d10, one labelled 00,10,20..90, the other normal.
Examples do exist of 'true' d100's, but these are rare, and given the nickname death stars due to a passing resemblance to the Star Wars ship. Other d100s may be in the shape of a golf ball. |
Often the names of the dice appear in formulas for calculating game parameters: e.g., hit points. '6d8+10', for example, will yield a number between 16 (6×1+10) and 58 (6×8+10) with a bell curve distribution, as it means 'Roll an eight-sided die six times and add ten to the total of all the rolls'. Occasionally they may be written '10×d6+20' or '1d6×10+20'; this means 'roll one six-sided die. Multiply it by ten and add twenty', and avoids boring repetitive dice-rolling at the expense of generating a bell curve distribution.
Polyhedal Dice in Role-Playing Games
Dungeons & Dragons is noted for introducing the use of many unique types of dice. While the game uses traditional 6-sided dice from time to time, many other types of dice are used more frequently. Most types of dice are used for numerous different purposes (such as weapon damage, spell damage, saving throws, character generation, etc.).
Players use polyhedral dice together in a number of ways. For example, often a d10 is used in conjunction with a d6 instead of using a d20. If the d6 displays a 1-3, the number on the d10 is resolved as 1-10. If the d6 displays a 4-6, the number shown on the d10 is resolved to 11-20 ("1" is 11, "2" is 12, etc.). In cases like this, almost any sided die can be used as a "resolver." However, d6 are preferred as they have the best "rolling" action (they don't roll too much, such as d20, d12, d10 or d8's may) and they actually roll, whereas d4's usually just sit where they are dropped.
Almost any die can be used for a throw where a binary result (true or false) is needed. In these cases, the player calls the meaning of the result as he throws the die, "One to three is true, four to six is false."
Two d10 (or two d20) are used for probability throws where a 1-100 result is needed. When tossing these dice, the player indicates which dice is "high" (representing the tens position). For example, "red is high."
The Earthdawn game system is notable for its "action step" table, which lists combinations of dice that are expected to produce average rolls from 1 to 40. This table is used for almost all die-rolling in the game.
Like with marbles, players often show favor for their own set of dice, and usually a fondness for one die within each type.
D&D dice are usually made of plastic, though infrequently metal and wooden dice can be found. Polyhedral dice can be purchased at most hobby stores in numerous combinations. In the early days of D&D, Most dice come with the numbers unpainted and players took great care in painting their sets of dice. Many early d20's came with two sides with the numbers zero through nine on them; one side had to be painted a contrasting color to signify the "high" side.
Players usually carry their dice in a linen or leather pouch or special box, sometimes specifically crafted for their dice. Throughout gameplay, players will normally use their own dice instead of sharing one set. Since dice are rolled so often during gameplay, this generally is required to expedite playing. The covert use of loaded dice is uncommon, though not unheard of, in D&D.