Some rules ask you to roll and reserve dice. This mechanic gives you partial control over the outcome of a roll and is generally used to represent a character carefully planning their actions. This rule only applies to ten-sided dice rolled as part of an attribute check, skill check or saving throw.
You may only have one set of reserved dice at a time. If you already have reserved dice, you must decide before rolling any new dice whether to keep your current set or replace it with the new set. Reserved dice can only be spent on the effects or abilities granted by the rule that required you to roll them.
When instructed to reserve dice, roll the specified number of dice and set them aside. Unless otherwise noted, the values rolled cannot be changed.
When instructed to play reserved dice, they are always used showing their original rolled value, and they replace dice that would otherwise be rolled. For example, when you Stand in Defence for another character, your reserved dice may be used as part of the aggressor's attack roll.