Some monsters are vulnerable to certain materials, such as alchemical silver, adamantine, or cold-forged iron. Attacks from weapons that are not made of the correct material have their damage reduced, even if the weapon has an enhancement bonus.
Some monsters are vulnerable to magic weapons. Any weapon with at least a +1 magical enhancement bonus on attack and damage rolls overcomes the damage reduction of these monsters. Such creatures’ natural weapons (but not their attacks with weapons) are treated as magic weapons for the purpose of overcoming damage reduction.
A few very powerful monsters are vulnerable only to epic weapons; that is, magic weapons with at least a +6 enhancement bonus. Such creatures’ natural weapons are also treated as epic weapons for the purpose of overcoming damage reduction.
Some monsters are vulnerable to chaotic-, evil-, good-, or lawful-aligned weapons. When a cleric casts align weapon, affected weapons might gain one or more of these properties, and certain magic weapons have these properties as well. A creature with an alignment subtype (chaotic, evil, good, or lawful) can overcome this type of damage reduction with its natural weapons and weapons it wields as if the weapons or natural weapons had an alignment (or alignments) that match the subtype(s) of the creature.
