[RPG] Can you knock out Animated Armor and/or Zombies

combatdamagednd-5enonlethal

When making a melee attack against a creature that reduces it to 0 HP the attacker can declare the attack incapacitating rather than lethal: "the attacker can make this choice the instant the damage is dealt. The creature falls unconscious and is stable." (PHB p.198, "Knocking a Creature Out")

Does this work on constructs and undead? Let's look at the specific cases of Animated Armor (MM p.19) and Zombies (MM pp.315-316):

  • neither require sleep by dint of their Constructed or Undead Nature;
  • neither is immune to the unconscious condition;
  • in case it matters, neither undead nor most constructs are susceptible to Sleep. (Undead are called out by name, most constructs inherit Sleep immunity from their immunity to being charmed. Modrons, however, are not immune to being charmed and thus not immune to being put to Sleep.)

For both creatures sleeping just isn't a thing they do. But it would appear that you can knock them out with a well-placed tap on the back of the head/helm?
(It gets even stranger when you start thinking about extending this thinking to a Flying Sword (MM p.20) or a Ghost (MM p.147).)

Best Answer

For Constructs (such as Animated Armor), no.

Monster Manual pg.19 covers this.

Constructed Nature.

An animated object doesn't require air, food, drink, or sleep. The magic that animates an object is dispelled when the construct drops to 0 hit points. An animated object reduced to 0 hit points becomes inanimate and is too damaged to be of much use or value to anyone.

As for golems, which are much more powerful construct, the answer is still no.

Monster Manual pg.167 covers this (emphasis mine):

Blind Obedience.

When its creator or possessor is on hand to command it, a golem performs flawlessly. If the golem is left without instructions or is incapacitated, it continues to follow its last orders to the best of its ability. When it can't fulfill its orders, a golem might react violently-or stand and do nothing. A golem that has been given conflicting orders sometimes alternates between them.

A golem can't think or act for itself. Though it understands its commands perfectly, it has no grasp of language beyond that understanding, and can't be reasoned with or tricked with words.

As for undead, yep, nothing seems to prevent that.

So I looked up ghouls, ghosts, skeletons, and zombies to see if any of them had the 0 HP limit like armor does. The answer is no. Interestingly enough, the skeletons can even use their brain and think through rudimentary problems. It seems undead have a little more agency in 5e. So it looks like you could knock out an undead, which makes sense. I mean, vampire spawns are undead, and they sleep, which means they have an unconscious state. Even mummies sleep until you step into the plot device that wakes them up.

Exception

Helmed Horror - MM pg.183 (Intelligent construct). It has Constructed Nature, but does not become useless armor at 0 HP as it is not explicitly stated. You could of course rule that Constructed Nature makes it that way, however a Helmed Horror is specifically imbued with actual Intelligence.