Additional Damage Dice: Some magic weapons deal additional dice of damage. Unlike other modifiers to damage, additional dice of damage are not multiplied when the attacker scores a
critical hit.
Spells,
spell-like abilities, and energy attacks (even non-magical fire) ignore damage reduction.
[ However, if a magical attack specifically mentions that it deals bludgeoning, piercing, or slashing damage,
DR affects that damage normally, as if it were from a physical weapon. ]
una bomba di fuoco da 30 danni addosso ad un drago rosso con RD 10/- e resistenza 20 al fuoco, quindi, farebbe 10 danni