explode `DIE`

This function yields the exploded version of the DIE. Exploding a die means that you keep rolling it as long as you roll its maximum possible value. The final result will be the sum of all the rolled values. For example, with one exploding d6 you could roll 6 + 6 + 6 + 4 for a total of 22.

Note that a dice collection will be treated as a single die. So [explode 2d6] will only explode when a total of 12 is rolled, in which case another 2d6 is rolled and added to the result. If you want the two d6 to explode independently, you can use 2d[explode d6].

It is theoretically possible to keep rolling the maximum value forever, although the chance of doing so is infinitely small. If AnyDice were to calculate this, it would take forever to complete. To prevent this from happening, AnyDice will only calculate a few extra rolls. A consequence of this is that the calculated odds will not be perfect. By default AnyDice explodes at most twice, which is a reasonable default, but you can set this to any positive amount you like.

Examples

output [explode d6]
output [explode 2d6]
output 2d [explode d6]

set "explode depth" to 1
output [explode d6]

set "explode depth" to 10
output [explode d6]

Note that the highest number listed in these outputs will actually never be rolled, because in reality the die would be rolled again. So it can be taken to mean "any possible result above this value".

Do it yourself

If the maximum function depth is set to 10 (the default), this function will work the same as the predefined explode function with explode depth set to 8. This assumes you're not calling the function from inside another function.

function: explode DIE:d {
 MAX: [maximum of DIE]
 result: [explode DIE helper]
}

function: explode N:n helper {
 if N = MAX { result: N + [explode DIE helper] }
 result: N
}

Variant explosions

If you want to keep rolling based on other criteria than the maximum possible value, you'll have to create your own function. Here is an example for exploding a d6 whenever the result is larger than 3.

function: explode N:n {
 if N > 3 { result: N + [explode d6] }
 result: N
}

set "maximum function depth" to 5
output [explode d6]

Because in this case the maximum function depth was set to 5, the explode function will roll at most five dice in a row. By default, the maximum depth is 10.