I think instead of just adding the ability to re-roll once, it should be the ability to re-roll any specified number of times. The biggest reason is I would love to be able to set up re-rolls to be the same number of times as the number of sides on a die. I think its the best way to handle damage escalation for different weapons in an rpg. Your butter-knife does 1d2, theoretical max damage would be 4. Your axe does 1d6 theoretical max damage would be 36 etc. I don't know if any established systems currently do things this way, but it is definitely the way I would handle things if/when I create(d) my own system. Not sure how difficult it would be compared to adding the ability to re-roll once, but if it isn't a crazy increase in work.... PLEASE????? PRETTY PLEASE????? There have to be other rpg's that need a re-roll a certain number of times other than once or infinite.