Can massive damage knock out rather than causing instant death?

Question

Suppose, as happened last night, a character intends to subdue rather than kill an opponent. She made a melee attack, hit, declared her intent to knock out. The damage roll was enough to reduce the opponent to zero and the remaining damage exceeded the opponent's maximum HP.

Now we would seem to have two rules invoked:

Instant Death. Massive damage can kill you instantly. When damage reduces you to 0 hit points and there is damage remaining, you die if the remaining damage equals or exceeds your hit point maximum. (PHB p.197)

Knocking a Creature Out. When an attacker reduces a creature to 0 hit points with a melee attack, the attacker can knock the creature out. The attacker can make this choice the instant the damage is dealt. The creature falls unconscious and is stable. (PHB p.198)

So which rule takes precedence? Or is it neither?

Answer 1

These rules have two entirely separate triggers, and if a single attack satisfies both, then so be it.

The attack reduced the creature to 0 hit points, and it was a melee attack. So you can choose to knock the creature out; it's now unconscious and stable.

However, there was leftover damage from the attack equaling or exceeding the creature's maximum hitpoints. So it dies.

The end result is that the creature is dead. If you're worried about realism, this is a perfect outcome: If you're trying to knock someone out, but you hit them hard enough to kill them, they die, regardless of your intentions.

Answer 2

The Creature is Unconscious

The rule for massive damage is (PHB p.197):

Massive damage can kill you instantly. When damage reduces you to 0 hit points and there is damage remaining, you die ...

The rule for Monsters and Death is (PHB p.198):

Most DMs have a monster die the instant it drops to 0 hit points, rather than having it fall unconscious and make death saving throws. Mighty villains and special nonplayer characters are common exceptions; the DM might have them fall unconscious and follow the same rules as player characters.

The massive damage rule applies to players, not monsters, remember this is the Player's Handbook - any beholders or dragons reading it are way out of line! A monster reduced to 0hp is dead unless there is an exception. One is that the DM wants to treat the monster like a player. Another is that the player wants to knock the monster out.

More importantly, which is the most fun?

Never forget that the primary rule of D&D is in the How to Play section on p.5:

1. The DM describes the environment. "Here is a monster."
2. The players describe what they want to do. "I want to knock it out."
3. The DM narrates the results o f the adventurers’ actions. "The monster is dead or The monster is unconscious

The dice decide nothing; they merely inform the DM's decision. Of course 99.9% of the time they inform it totally but when they don't, the DM can use whatever they like in deciding between these two outcomes; not least the Rule of Cool and the potential consequences of the Accidental Murder. Which one you choose depends on which one gives the player's the best shot at awesome.

Answer 3

No, instant death supersedes a nonlethal knock-out.

When you reduce a creature to 0 hit points with a melee attack, you can choose to nonlethally knock them out. However, when you not only reduce a creature to 0 hit points but also deal enough excess damage to exceed their maximum hit points, they die.

In D&D 5e, specific beats general. In this case, these are both specific rules for specific situations. However, both rules have a condition of reducing a creature to 0 hit points, while only one of them stipulates an additional condition and is therefore more specific.

So, the massive damage rule causing instant death supersedes the nonlethal rule for merely knocking a creature out because it applies to a more specific scenario. This also makes sense thematically because it's entirely possible to try to bop somebody unconscious and accidentally manslaughter them to death.

Answer 4

This will likely require arbitration and a ruling by the DM

Here's the problem. Specific beats general. Except in this case, you have two specific rules countering one general rule.

The general rule for creature death is in the PHB pg.198:

Most DMs have a monster die the instant it drops to 0 hit points, rather than having it fall unconscious and make death saving throws.

Mighty villains and special nonplayer characters are common exceptions; the DM might have them fall unconscious and follow the same rules as player characters.

The exceptions, which are specific overrides to this are Instant Death and Knocking a Creature Out.

You've already cited both of these sources in your question, so I'll break it down.

• Instant Death - specific rule that occurs if and only if maximum damage is applied to a character/creature that exceeds it's maximum health, taking into account damage required to reduce it to an unconscious state. This means a target with 9 HP left out of 15 HP total would require a total of 24 damage to be dealt in a single turn in order to kill it outright.

• Knocking a Creature Out - specific rule that occurs upon dropping a target to 0 HP. You can elect to deal this nonlethal damage on the instance of attack.

Now, why is this a DM decision? Because even a nonlethal attack can end up becoming a lethal attack by accident. Let's say you take a swing at a very wounded goblin and declare nonlethal intent to knock the creature out. So you roll your attack and score a critical hit.... and you're playing a Half-Orc so you also have Savage Attacker bolstering your blow.

The damage you deal is reflective of the attack that has been made. Which means a critical, nonlethal blow means you screwed up. For instance, I would narrate that as, "You hit the target in the head with the flat of your blade to knock it out, but in it's weakened state you snapped it's neck with the force of your blow." (Or something similar among those lines, like internal bleeding)

Neither of these specific rules take precedent over the other though. So you could also rule as the DM that the nonlethal intent is always successful and thus the damage is irrelevant so long as it is enough to render a target unconscious.

What this boils down to is a rare case where two specific rules conflict, so arbitration becomes a requirement if there is disagreement. Ultimately, rolling high/low might be the easiest way to determine the outcome when torn between two choices.

Answer 5

The monster is unconscious.

The rules on knocking a creature out state that (PHB, p. 198; bold added by me):

When an attacker reduces a creature to 0 hit points with a melee attack, the attacker can knock the creature out. The attacker can make this choice the instant the damage is dealt. The creature falls unconscious and is stable.

The instant death rule states that (PHB, p. 197; bold added by me)

Massive damage can kill you instantly. When damage reduces you to 0 hit points and there is damage remaining, you die if the remaining damage equals or exceeds your hit point maximum.

Therefore, after you are reduced to 0 hit points, the remaining damage from the same source is not applied, and only used if it is greater than or equal to your maximum hit points. So we see that the damage at 0 hit points is separate from the original damage. Since the rules for knocking out say that the creature becomes unconscious and stable, the creature is stable and it would not die, as the rules on stabilizing a creature state (italics added by me):

A stable creature doesn’t make death saving throws, even though it has 0 hit points, but it does remain unconscious.

Answer 6

RAW

Miniman is right; the enemy is dead.

How I interpret it

If you consider the spirit of the rules, as in rulings over rules:

A good attack roll does not mean big wounds, it means big success. The character wanted to knock out the enemy, and she succeeded. Rolling a lot of damage means it was knocked out unusually thoroughly.

A bad attack roll means failure. In this case, she wanted to subdue the opponent, a roll of 2 (failure) means an absence of success, and only roll of 1 (critical failure) takes away even the chance of success in the future.

So I would rule that the target is incapacitated on a 20, and killed only on a 1.