[RPG] Is sneak attack affected by resistance/immunity to weapon attacks


Sneak attack says:

Once per turn, you can deal an extra 1d6 damage to one creature you hit with an attack if you have advantage on the attack roll. The attack must use a finesse or a ranged weapon.

Would the extra damage from sneak attack bypass the resistance of a creature that had damage resistance/immunity to damage from weapons?

Damage Immunities: Bludgeoning, piercing, and slashing from nonmagical weapons

One aspect I am specifically curious about is that sneak attack does not say that it is weapon damage (nor does it say it isn't); all it says is that it is "extra damage". Is sneak attack considered to be damage from a weapon or is it something separate?

For example, consider the case of a rogue with a nonmagical dagger hitting a creature with the above damage immunity. Obviously the dagger does not do any damage, but what about the sneak attack damage? What about when the creature only has resistance?

Best Answer

Resistance/Immunity would apply (because the rule used in the question is defunct)

It's debatable whether or not sneak attack's damage is from the weapon: but one thing I can be sure of is that sneak attack damage is from the attack. This can be seen in the PHB (p. 196, bold added), where it states:

When you score a critical hit, you get to roll extra dice for the attack’s damage against the target... If the attack involves other damage dice, such as from the rogue’s Sneak Attack feature, you roll those dice twice as well.

That's very important, because the rule you're quoting about "nonmagical weapons" is now defunct. See the Monster Manual Errata which states:

Damage Resistances/Immunities. Throughout the book, instances of “nonmagical weapons” in Damage Resistances/Immunities entries have been replaced with “nonmagical attacks.”

The same errata goes further, explaining what magical attacks actually are (and implies what they aren't):

Particular creatures are even resistant or immune to damage from nonmagical attacks (a magical attack is an attack delivered by a spell, a magic item, or another magical source). (MM, p. 8 post errata)

And rules designers have explicitly stated that sneak attack is intended to do the same type of damage as the weapon used in the attack. Jeremy Crawford has stated:

Sneak Attack damage is meant to be of the type that's dealt by the weapon, and it's subject to resistance.

So although it may be debatable whether or not sneak attack damage comes from the rogue's weapon, it definitely is part of an attack and will do "bludgeoning, piercing, or slashing" damage if that's the type of damage done by your weapon. And so, if the weapon used in this attack is a nonmagical dagger, sneak attack is part of a nonmagical attack and would deal piercing damage, and thus the resistance/immunity to "piercing... from a nonmagical attack" would apply.