Inspired by a thread on the EN World forums, I have decided to get some use out of my beloved d30.
Once per session each person at the table (DM included) may roll a d30 instead of whatever die or dice the situation normally warrants. The decision to use the d30 must be made before the roll. If used for an attack roll, the threat range is extended from the normal range through to 30.
Why do we need this rule? We don't. I'm simply a mad-with-power house-rulin' fool!