Quote from Haravikk >>

Quote from TheAlmightyN >>

Quote from Haravikk >>

I would argue the spell still killed you in this case, as the skeletons wouldn't have been able to finish you off without it being cast first.

The rules are only interested in what actually killed you. If you failed three death saves, that is what killed you regardless of how you may phrase it in conversation, e.g. "Remember when you were killed by that weak little goblin har har har?"

By that logic you are effectively rendering this spell useless; because technically you cannot kill anything with it unless you are forcing the final failed death save, that's one hell of a nerf to a 7th level spell.

If you reduce a creature to 0 hit-points with this spell then the spell is the reason that that creature is dying.

This holds true with medical cause of death; if a person falls and breaks their neck, it's the broken neck that kills them, even if they survive for a few hours before suffering organ failure (due to no signals from the brain).

I'm not sure why you want to nerf a 7th-level spell that's very, very clear in how it's intended to work?

EDIT: Making my point clearer and more personable. Apologies for original post being rude.

If I may, this is a moot point. Normal NPCs do not make death saving throws, they die when reaching 0 hit points. The rule is open to exception as per the DM, but is not nonexistent. In the hands of players, the spell leaves no room for misinterpretation RAW against average enemies.

Any confusion comes about from using the spell against PCs or Special NPCS (aka. the exceptions). In such a case, RAW also clearly dictates that only the instance of damage that results in a third death saving throw or massive damage (eg, -100% hit points) would count as a killing blow. This has been confirmed by Jeremy Crawford, and is clear in the PHB. When at 0 hit points, you are not yet dead and have not been restored to life, therefore have not been killed.

If you'd like to play otherwise, it is the business of your group and none else, and you have the right to do so, even if it causes you to change additional rules to accommodate. D&D has a number of rules that state common alternatives or exceptions, but is balanced, written, and designed around the RAW. This spell is written as is assuming that the majority, if not entirety, of your enemies will die at 0 hit points. Ergo, it has a slightly reduced damage potential, a relatively easy save, and a powerful special effect to balance itself.

Seems you have two primary options if you'd like to play this way:

"For the purposes of effects triggered by killing their target, the target is killed by the last instance of damage that it was subjected to." (eg. your "the fall killed them, not asphyxiation" logic). This reasons that if you are reduced to 0 hit points by this spell, then fail the naturally resultant death saves, the spell killed you. If a skeleton stabs you, giving you one more death save, the skeleton killed you. This follows proper forensic logic that you cited.

Or, the more abstract way in which games function, alter the spell to be as such:

"On a failed save, If the target is a humanoid, upon being reduced to 0 hit points by this spell it dies and rises at the start of your next turn as a zombie that is permanently under your command, following your verbal orders to the best of its ability."

Nothing posted on twitter is an official ruling. It might be what that particular designer believes, but that's it. There is far more than one designer's opinion that goes into making rules for the game.

Think about this: If a player's character is stabbed with a dagger, fails three saves, and dies, what killed them? It is being extremely pedantic, if you say that the dagger did not kill them, because it took them up to 30 seconds to bleed out, and therefore it was not the dagger, but the bleeding that did it. The same would apply to this spell, when used against players. The player was dealt lethal damage by this spell, and their body took up to 30 seconds to cease functioning after that. Then they come back as a zombie.

Letting the player have their death saves is good practice though. It's not fun to have a character instantly die without any recourse--and it's in the rules.

Quote from Haravikk >>

Quote from TheAlmightyN >>

Quote from Haravikk >>

I would argue the spell still killed you in this case, as the skeletons wouldn't have been able to finish you off without it being cast first.

The rules are only interested in what actually killed you. If you failed three death saves, that is what killed you regardless of how you may phrase it in conversation, e.g. "Remember when you were killed by that weak little goblin har har har?"

By that logic you are effectively rendering this spell useless; because technically you cannot kill anything with it unless you are forcing the final failed death save, that's one hell of a nerf to a 7th level spell.

If you reduce a creature to 0 hit-points with this spell then the spell is the reason that that creature is dying.

This holds true with medical cause of death; if a person falls and breaks their neck, it's the broken neck that kills them, even if they survive for a few hours before suffering organ failure (due to no signals from the brain).

I'm not sure why you want to nerf a 7th-level spell that's very, very clear in how it's intended to work?

 non-player characters and other creatures in DnD die immediately when reduced to 0 HP they do not roll Death saves. so it is not a nerf to the spell to kill anything but the PCs. That is how the spell was intended since 5e was designed to make it hard for PCs to immediately because the designers felt that it would lead to bad moments if players died instantly. Because of that, there are very effects that kill players outright. 

TLDR; the spell works as intended. NPCs and creatures reduced to 0 HP immediately die and are therefore turned into Zombies. PCs RAWs do not die outright when reduced to 0 unless specified in the Description of an effect (see for example the necrotic ray of a Beholder) so they are not turned into zombies by this spell.

So you are probably a worse person than vecna himself because it means you killed at least 1 million humanoids. making you one of the worst calamities that happened in DnD history so far.

"I cast gun prepare to meet god"