An override die is a trick a DM can use to bend an existing random table or procedure in order to favor a particular result.

1. A DM uses the random encounter tables in Appendix C, but always rolls a d10 along with the percentile dice. If the d10 shows a 1, the DM places a homebrew monster instead of the monster shown on the percentile dice.
2. A DM uses the standard alignment chances mentioned in the henchmen generation rules, but rolls a d6 along with them. If the d6 shows a 1 or 2, the rolled alignment is ignored in favor of the prevailing alignment of the settlement.
3. An example straight from the rules: Magic items are rolled for with percentile dice, but a d10 is rolled along with them. If the d10 shows a 1, a treasure map is placed instead.