explodingdice

Exploding dice is a die-rolling mechanic used in many tabletop role-playing games and other dice-based games, where rolling the maximum value on a die triggers an additional roll that is added to the result. If that additional roll also comes up maximum, it is rolled again, and so on, until a roll that is not the maximum occurs or a game-imposed limit stops the chain. The effect is to increase the odds of very high totals and to add volatility to outcomes.

In a game using exploding d6s, rolling a 6 on a single die adds another d6 to the total; if that new roll is also a 6, another d6 is added, etc. When multiple dice are rolled in a pool, each exploding die continues independently. Some systems cap the number of explosions or place a hard limit on the final total to keep outcomes bounded.

Variants include open-ended dice, where explosions trigger on the maximum face, or other thresholds and rules that modify when explosions occur or how they are counted. Some games also distinguish between single-die explosions and multiple-dice explosions, or use explosions only in certain situations (such as critical attempts or high-difficulty tasks).

Probability and balance: for a die with m sides that explodes on its maximum, the expected value is m(m+1)/(2(m-1)). For a d6, this equals 4.2, higher than the standard 3.5. Exploding dice thus increase average outcomes and introduce the possibility of very large results, influencing strategy and risk assessment in play.