[RPG] Can a Paladin use Divine Smite when attacking (with a natural 20) a creature immune to the weapon’s damage type


Prompted by this question about Sneak Attack and Immunities, it seems a character can hit (although for 0 damage) with a weapon which deals damage to which the target is immune.

What would be the result if a Paladin rolled a 20 (with a non-magical slashing weapon), attacking a creature immune to non-magical slashing damage, if the Paladin casts Divine Smite?

Note: I specify a natural 20 in the actual question to avoid discussion about armor class when considering the result.

Best Answer

Divine smite only requires you to hit, which immunity does not prevent

Some creatures have vulnerability, resistance, or immunity to certain types of damage. Particular creatures are even resistant or immune to damage from non-magical attacks [...]

Being immune means you are immune to damage from that particular damage type/attack. It doesn't make you immune from getting hit with that attack.

Divine Smite only requires you to hit with a melee weapon attack:

when you hit a creature with a melee weapon attack

Thus, the paladin can activate Divine Smite on a creature immune to the weapon's damage type as long as it hits.

On a crit: No weapon damage is taken, but the smite's radiant damage is rolled twice

The result of the attack (with crit) would be that the divine smite damage would be rolled twice and no damage from the weapon itself would apply. Since Divine Smite has a damage type of radiant and is magical (it is fueled by spell slots) it will apply as long as the monster isn't immune to radiant damage.