Rule[]
Dice can be modified in the following ways by game effects:
- Reroll: When a die is rerolled, the attacker picks it up and rolls it again. A die can be rerolled multiple times.
- Add: When a die is added, roll an unused die of the appropriate color into the attack pool.
- The range restriction on dice color applies only when dice are gathered during the "Roll Attack Dice" step of an attack.
- Change: When a die is changed, rotate it to display the indicated face.
- Spend: When a die or die icon is spent, remove that die from the attack pool.
- Cancel: When a die or die icon is canceled, remove it from the attack pool.
- Replace: When a die is replaced by another die, the first die is removed from the attack pool and the second die takes its place as indicated by the effect.
- Exchange: When a die is exchanged for another die, the first die is removed from the attack pool and the second die takes its place as indicated by the effect.
- Set: When a die is set, place it in the attack pool, with the relevant result face-up, as indicated by the effect.
- Remove: When a die is removed, it is removed from the attack pool.
Source: RRG 1.5.0 p.11 / Rules Reference Corrections and Useful Links, 29 June 2021
Timing[]
Dice are (normally) modified during Attack step 3: Resolve Attack Effects. To cancel dice during Attack step 4: Spend Defense Tokens with 
or 
defense tokens is also an act of modifying dice.