Does the DMG's "Disarm" bypass AC?

Question

In the DMG at pg. 271 the disarm described appears to bypass the defenders AC: it is a contest of attack roll vs. skill. There is no mention of AC being a factor.

So could a L1 human fighter tavern brawler with a shield and no other weapon attack a defender (using the shield as an improvised weapon), declare they are attempting a disarm before damage is rolled, if successful disarm the defender, then grapple as a bonus action and finally move the defender from their just-dropped weapon by 15ft?

Answer 1

Yes.

As you noticed in the DMG, a disarm attempt is a hybrid attack/contest: attacker's attack roll against defender's athletics or acrobatics check.

As to your specific example, you've (basically) got it all right there, too. Let's step through it.

a lvl 1 Human Fighter with a shield and no other weapon could attack the defender with a shield (Tavern Brawler)

Yes. It'll be as an improvised weapon, but nicely for a tavern brawler he'll be proficient.

declare they are attempting a disarm before damage is rolled (atk vs skill)

I believe you would have to declare that the attack is a disarm attempt before the attack roll, not after the attack roll but before any damage, as this seems to imply. The reasoning: if you could see the attack roll, you know it doesn't beat the AC, then declare "oh, I was trying to disarm," then that stinks mightily of cheese.

and if successful disarm the defender

Yup, per "disarm" in the DMG,

then grapple as a bonus action

Yup, per tavern brawler,

and move the defender from their weapon by 15ft?

Yup, per "Grappling," PHB p.195 (assuming your base speed's 30').

Answer 2

Yes

First: disarming doesn't do damage, so it's a special kind of contest. AC doesn't come into it because you aren't attacking the person, you're attacking their weapon. This is similar to a grapple attempt in that it's a contest, not an attack.

Second: They need to be able to be disarmed of something. In your scenario, the only thing that could be disarmed is the target's shield (your scenario is unclear on their weapons).

Third: The attacker can use a weapon attack (which unarmed strikes qualify for as per the errata), but the target can only be disarmed of a weapon or other item in their grasp. This means you can't disarm an unarmed opponent, or an opponent wearing something instead of carrying it in their hand, like gauntlets, a helmet, a necklace, etc.

Lastly: You can shove the target back and just pick up the weapon from the ground if you want. Your scenario specifies you are unarmed, so shoving them away from the weapon and picking it up isn't a particular problem. Picking something up off the ground doesn't take an action. Interacting with multiple things does.

From Disarm rules in DMG pg. 271:

A creature can use a weapon attack to knock a weapon or another item from a target's grasp. The attacker makes an attack roll contested by the target's Strength (Athletics) check or Dexterity (Acrobatics) check. If the attacker wins the contest, the attack causes no damage or other ill effect, but the defender drops the item.The attacker has disadvantage on its attack roll if the target is holding the item with two or more hands. The target has advantage on its ability check if it is larger than the attacking creature, or disadvantage if it is smaller.

Answer 3

Yes, it works the way you describe. It is a rare situation, a contest between an attack roll and a skill check.

Because you are making an attack roll, features like dual wielding and polearm mastery butt strike and tavern brawler grapple will all apply.

Note that Battlemaster Fighters have a special option - they can do damage and disarm in the same attack.

As an aside, whether or not you can disarm someone of their shield is not clearly defined out by the rules. I rule that you can't, because shields are worn not grasped (they take 1 round to don and doff).

Whether or not you can disarm someone using your shield (i.e. is a shield an improvised weapon) is also not clear. I rule that shields are not weapons, improvised or not, because they are worn, not grasped. However, I house rule that unarmed attacks do more damage if the attacking character is armoured, which includes wearing a shield. Wearing heavy armour means that your punches and kicks and elbow strikes do more damage.