Step 3: Apply the Target’s Immunities, Vulnerabilities and Resistances
Defenses against certain types of damage or effects are called immunities or resistances, while weaknesses are called vulnerabilities. Apply immunities first, then vulnerabilities and resistances third.
Immunity
When you have immunity to a specific type of damage, you ignore all damage of that type. If you have immunity to a specific condition or type of effect, you can’t be affected by that condition or any effect of that type. You can still be targeted by an ability that includes an effect or condition you are immune to; you just don’t apply that particular effect or condition.
If you have immunity to effects with a certain trait (such as death effects, poison, or disease), you are unaffected by effects with that trait. Often, an effect has a trait and deals that type of damage (this is especially true in the case of elemental damage types). In these cases, the immunity applies to the effect corresponding to the trait, not just the damage. However, some complex effects might have parts that affect you even if you’re immune to one of the effect’s traits; for instance, a spell that deals both fire and acid damage can still deal acid damage to you even if you’re immune to fire.
Immunity to critical hits works a little differently. When a creature immune to critical hits is critically hit by a Strike or other attack that deals damage, it takes normal damage instead of increased damage. This does not make it immune to any other critical success effects of other actions that have the attack trait (such as Grapple and Shove).
Another exception is immunity to non-lethal attacks. If you are immune to non-lethal attacks, you are immune to all damage from attacks with the non-lethal trait, no matter what other type the damage has. For instance, a stone golem has immunity to non-lethal attacks. This means that no matter how hard you hit it with your fist, you’re not going to damage it (unless your fists don’t have the nonlethal trait, such as if you’re a monk).
Temporary Immunity
Some effects grant you immunity to the same effect for a set amount of time. If an effect grants you temporary immunity, repeated applications of that effect don’t affect you for as long as the temporary immunity lasts. Unless the effect says it applies only to a certain creature’s ability, it doesn’t matter who created the effect. For example, the blindness spell says, “The target is temporarily immune to blindness for 1 minute.” If anyone casts blindness on that creature again before 1 minute passes, the spell has no effect.
Temporary immunity doesn’t prevent or end ongoing effects of the source of the temporary immunity. For example, if an ability makes you frightened and you then gain temporary immunity to the ability, you don’t immediately lose the frightened condition due to the immunity you just gained - you simply don’t become frightened if you’re targeted by the ability again before the immunity ends.
Resistance and Vulnerability
Some creatures and objects are exceedingly difficult or unusually easy to hurt with certain types of damage.
If a creature or an object has resistance to a damage type, damage of that type is halved against it. If a creature or an object has vulnerability to a damage type, damage of that type is increased by 50% against it.
Resistance and then vulnerability are applied after all other modifiers to damage. For example, a creature has resistance to bludgeoning damage and is hit by an attack that deals 25 bludgeoning damage. The creature is also within a magical aura that reduces all damage by 5. The 25 damage is first reduced by 5 and then halved, so the creature takes 10 damage.
Multiple Instances of resistance or vulnerability that affect the same damage type stack as follows:
| Instances of Resistance or Vulnerability | Damage Change in Percent (%) |
|---|---|
| 1 | 50% |
| 2 | 70% |
| 3 | 80% |
| 4 | 85% |
| 5 | 90% |
| 6 | 95% |
| 7 | 100% |