Immune to <Type> Weapons: Some monsters are immune to certain types of weapon attacks in addition to its regular immunities. Any attack that has the verbal of what the monster is immune to in it will not affect the monster.

Immune to Normal weapon attacks (example: some lesser undead)
Immune to Normal and Silver weapon attacks (example: some greater undead)
Immune to Silver and Magic weapon attacks (example: some fae)
Some monsters require special weapons in order to be affected by a weapon attack. In these cases, the weapon attack must include the verbal the monster is affected by, or the monster calls “no effect.” Examples:
Only affected by Healing, Silver or Magic weapon attacks. (example: some lesser undead)
Only affected by Healing or Magic weapon attacks. (example: some greater undead)
Only affected by Silver weapon attacks. (example: a werewolf)
Only affected by Normal weapon attacks. (example: some fae)
Only affected by Magic weapon attacks. (example: a bone golem)
Only affected by Magic or Doom weapon attacks (example: a life elemental)

Keep in mind that other immunities also play into this. For example, a life elemental that is affected by Doom weapon attacks would still be unaffected by a “10 Poison Doom” attack if it is Immune to poisons. Also keep in mind, a creature that is “healed” by an effect is also Immune to that effect as a carrier. For example, a zombie that is “Healed by Necromancy” would be immune to the weapon attack “2 Chaos.”