Monster DR and weaknesses

Monsters may be resistant to or fully protected from some forms of attack and vulnerable to others.

For reference, "normal" damage is shown with red numbers. Resistances (via DR) are indicated by yellow damage numbers: this means some of your damage is being reduced and it might be possible for you to overcome this by changing weapon type. Full protection is indicated by white zero damage numbers. Some forms of damage are particularly effective against a monster and this is indicated by pink damage numbers.

Please feel free to update the following list:
 * Ancient arachnid: DR/piercing
 * Bezekira: DR/Cold iron and good
 * Clay golem: DR/bludgeoning and adamantine
 * Dragon: DR/magic (not all dragons have it in PnP, for DDO i don't know)
 * Earth elemental: DR/-; vulnerable to Command, Hypnotism, Hypnotic pattern and Otto's resistible dance
 * Fire reaver: DR/Cold iron and good, vulnerable to cold, immune to fire
 * Fire elemental: DR/-, vulnerable to cold
 * Iron golem: DR/adamantine
 * Jarilith: DR/Cold iron and good, immune to electricity
 * Lich: DR/bludgeoning and magic
 * Marilith: DR/Cold iron and good
 * Marut: DR/Chaotic
 * Mephits: DR/magic
 * Mummy: DR/-, vulnerable to fire
 * Rakshasa: DR/piercing and good
 * Squeletton DR/bludgeoning
 * Zombie: DR/slashing

Thanks to contributors in this [DDO EU discussion].