
If you use "/roll 1d6r<7" it will reroll that d6 forever. I would not suggest testing it in a normal campaign as I was forced to delete my campaign to remove the problem. Luckily I was currently in a test campaign. As for how I found out I was setting up a macro to do "4d6 drop the low" for a custom campaign where the DM also wanted us to reroll any scores of 6 or lower. I was hoping that I could do "/roll {4d6d1}r<7" and that it would roll 4 dice, drop the lowest and if that was less than 7 it would reroll them all again. I would not be surprised if this happens in a campaign at some point.