From the Manufacturer
We devoted each colour to a different Celtic hero or deity: Black and red dice are the dice of war goddess Badb that is named “Deity of Crows” and can foreshadow imminent bloodbaths. All rolls of these dice can create confusion among the soldiers and can be used as a harbinger of doom for all of your character enemies. This is the last war-goddess set. If you have all three your player should be frightened because power of all bloodthirsty Morrigna are in your possession.