Resistances and vulnerabilities have also been reworked to allow for more interesting enemy stat block design should the DM choose to use these rules.

These new resistances and vulnerabilities only apply to enemy stat blocks, and do not affect player features, spells, or other mechanics that grant resistances or vulnerabilities.

Resistances and vulnerabilities now are calculated in tiers; as an example, a skeleton may have vulnerability 1 to bludgeoning damage, or a vampire might have resistance 3 to necrotic damage. When a creature with a resistance or vulnerability suffers damage of a relevant type, the damage is reduced or increased by a number of d4 equal to the creature’s resistance or vulnerability level.

• In the given examples from before: a skeleton being hit by bludgeoning damage would receive one additional d4’s worth of damage of that type when they are hit, and a vampire would receive 3d4 less damage when receiving necrotic damage.

• Vulnerability damage is calculated with the attack’s damage, so a critical hit with a vulnerable damage type would double the number of d4s rolled for the attack.
• Ideally, this allows DMs to add both more resistances and vulnerabilities to monsters they create. Players discovering a vulnerability will not break the combat, but will feel rewarding for the players to learn and try to use. Similarly the DM adding more resistances even to simple statblocks will give them just a little bit more texture, without invalidating players who run into these resistances and cannot overcome them with their usual tools.