D&D 5E Adamantine and the Shield spell

[Esker]

Normally a natural 20 on an attack roll automatically hits, regardless of the modified value and the targets AC. This also means that abilities or spells that boost AC (such as the Shield spell), along with abilities that dock the attack roll after the fact (Cutting Words, Bane, etc.) are impotent to stop crits.

Meanwhile, adamantine armor (as well as the Grave Cleric ability Sentinel at Death's Door) turns critical hits into normal hits.

How do these interact? Is a natural 20 vs someone wearing adamantine armor still an auto-hit, or is it just a 20+modifier, that can be turned into a miss with an ability that can turn hits into misses? Or does it depend on the ability?

It would seem that the Shield spell cast by a character wearing adamantine could perhaps turn a natural 20 into a miss, provided the +5 gets their AC above the modified roll, since the spell is cast in reaction to being hit by an attack. But it's not clear; I could see ruling that the fact that the attack hits (as a normal hit, due to adamantine) is independent of the target's AC.

Things like Cutting Words or Bane are I think clearer, since they are technically applied before any hit or miss determination is made, so I would think they wouldn't help.

Has anybody dealt with this interaction? If so, how did you handle it?

 

[Mort]

I don't change the fact that a 20 is still an auto hit. Adamantine just means it's not a critical (no doubling).

 

[DND_Reborn]

I think it is clear, for me anyway.

"If the d20 roll for an attack is a 20, the attack hits regardless of any modifiers or the target’s AC. In addition, the attack is a critical hit, as explained later in this chapter."

The attack always hits and is a critical. Adamantine only removes the critical property, the attack still hits, but does normal damage.

Features used after the fact won't change a hit into a miss (such as the Shield spell), unless the feature actually says "the attack misses", in which case it is specific trumping general. I am sure there might be a feature that does this, but none come to mind.

Hope all that makes sense.

 

[Esker]

"If the d20 roll for an attack is a 20, the attack hits regardless of any modifiers or the target’s AC. In addition, the attack is a critical hit, as explained later in this chapter."

Ah, yeah, the clause about hitting regardless of modifiers and AC is separate from the status as a critical hit. That does seem to make it pretty clear.

I've been watching a streamed game where the DM is usually pretty by-the-book. One of the characters is a Grave Cleric and another is a Lore Bard, and the DM lets the Grave Cleric use Sentinel at Deaths Door to cancel a crit, and then the Lore Bard to use Cutting Words to potentially turn it into a miss. It's a cool bit of teamwork, but I think not RAW.

 

[DND_Reborn]

Ah, yeah, the clause about hitting regardless of modifiers and AC is separate from the status as a critical hit. That does seem to make it pretty clear.

I've been watching a streamed game where the DM is usually pretty by-the-book. One of the characters is a Grave Cleric and another is a Lore Bard, and the DM lets the Grave Cleric use Sentinel at Deaths Door to cancel a crit, and then the Lore Bard to use Cutting Words to potentially turn it into a miss. It's a cool bit of teamwork, but I think not RAW.

This is one example of why when I DM I don't roll in the open. If the Bard wanted to use Cutting Words, he would have to do so after I roll, but without the knowledge the roll was a 20.

Also, RAW IMO, the Lore Bard couldn't use Cutting Words because if I, as DM, already declared a critical hit, invoking the Grave Cleric to use Sentinel at Death's Door, the result of the attack is known. Cutting Words can't be used once the result of the die roll is made.

If the DM is allowing the Bard to use Cutting Words after the attack is declared a critical, and thus a hit, it is too late and he is definitely not playing RAW.

 

[Paul Farquhar]

And conversely, the Champion's ability to crit on a 19 or 20 does not work if a 19 is a miss.

Likewise, special magic weapon abilities that function on a roll of 20 are not blocked by admantine armour.