Currently, 1d20!p rolls 1d20, and then adds another 1d20-1 if the first die rolled a max roll However, in Hackmaster 5th Edition, and presumably in some other systems or circumstances, you do not always roll the same-sized die when you explode or penetrate. In HM5, max on a 1d20 penetrates uses a 1d6-1, and 1d100 penetrates using a 1d20. I would like the ability to specify what penetrating die should be rolled, on a max result. Something like 1d20!p(1d6) in order to specify that on max result, a 1d6-1 should be rolled and added in, rather than a 1d20-1 1d20!(1d6) would be the same, except without the -1 on the subsequent rolls.