D&D 3E/3.5 Overcoming DR in 3.5

Simple question: when creating a new monster, how does one determine whether it can overcome any type of damage reduction? Does one assume that it can overcome any type of material-based DR that it has itself (i.e., lycanthropic attacks overcome DR/silver, whereas Golem attacks overcome DR/magic), and creatures with alignment-based DR overcome DR based on opposite alignments? Is there any sort of general rule?

Daniel

As far as I can see in the Monster Manual, it varies. Lycanthropes don't get any special weapon qualities. Vampires' natural weapons are treated as magical weapons for the purpose of overcoming DR, as are young adult and older dragons.

Demons treat natural and wielded weapons as Chaotic and Evil aligned, but not magical. Devil's weaponry is Lawful and Evil aligned. As has been noted in the 3.5 changes threads, Demons and Devils are not good at damaging each other, which changes the Blood War game world mechanics (they'll be wanting cold iron and silver weapons).

Angels: good aligned weaponry, Solars get epic as well.

Tarrasque has epic natural weaponry.

Hound and Trumpet Archons: lawful and good aligned weaponry.

Night Hags get evil-aligned natural and wielded, and magical natural weaponry.

Nightmares get evil-aligned natural and wielded.

Nightshades get magic natural weapons.

Titans get chaotic natural and wielded weaponry.

Elementals get nothing.

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Hmmm ... how's this for a rough approach:

Aligned outsiders (demons, devils, angels, etc.), get their alignment for natural and wielded weapons. Some of the powerful ones get magic natural weaponry as well.

Powerful Dragons and Undead get magic natural weaponry.

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With smart choices of summoned creatures, you can certainly slow your opposition down: summon monsters that they can't easily penetrate the DR of.

As I recall seeing it explained by someone official (possibly Andy Collins):

1. Those creatures that have DR X/magic have natural weapons that are also treated as magic.

2. Outsiders with an alignment subtype treat both their natural weapons as well as any melee weapon they wield as having that alignment. This might have been generic for all things with alignment subtypes, but I'm pretty sure it only applied to outsiders.

3. Unless the creature is actually made from a special material, it won't penetrate that material's DR.