Some effects will instruct players to upgrade or downgrade a unit’s attack or defense dice. When a die is upgraded or downgraded, it is removed from the Attack or Defense pool and the corresponding die it was upgraded or downgraded to is added. If the color of a die being upgraded or downgraded is not specified by the effect, the player controlling that effect may choose which dice are upgraded or downgraded. A die cannot be upgraded or downgraded more than once by the same effect.When upgrading attack dice, a white attack die is upgraded to a black attack die, and a black attack die is upgraded to a red attack die. A red attack die cannot be upgraded.When downgrading attack dice, a red attack die is downgraded to a black attack die, and a black attack die is downgraded to a white attack die. A white attack die cannot be downgraded.When upgrading defense dice, a white defense die is upgraded to a red defense die. A red defense die cannot be upgraded. 