> This is of course hilariously cursed. It will look almost perfect, but very rarely give numbers outside the expected range.
If the D65538 is fair, it is usable: you just discard the two unwanted values when they show up and roll again. Those faces could be labelled as "roll again".
If you have a uniform source of random numbers from 1 to N, you can get a uniform distribution from 1 to M < N simply by discarding values obtained above M. Those values are just "rain that fell elsewhere".
If the D65538 is fair, it is usable: you just discard the two unwanted values when they show up and roll again. Those faces could be labelled as "roll again".
If you have a uniform source of random numbers from 1 to N, you can get a uniform distribution from 1 to M < N simply by discarding values obtained above M. Those values are just "rain that fell elsewhere".