Defense against implosion

[Aldrakan]

I think it's obvious that the text is somewhat ambiguous on this point, but I'm going to make my own argument in terms of elegance.

Here's the text of the spell taken from SRD:

"The subject is immune to all death spells, magical death effects, energy drain, and any negative energy effects.
This spell doesn’t remove negative levels that the subject has already gained, nor does it affect the saving throw necessary 24 hours after gaining a negative level.
Death ward does not protect against other sorts of attacks even if those attacks might be lethal."

As I see it there are two versions of death ward being proposed in this discussion. One protects against negative energy effects and [death] effects, the other protects against spells that cause death, and also negative energy effects.
The first doesn't protect against implosion, because that works by creating a destructive resonance that makes the body implode, and as a result the person dies. That is obviously how it works, because 1. that's what the spell description says it does and 2. it doesn't work against noncorporeal creatures because they don't have a body to implode. Nor does it protect against phantasmal killer, because that works by scaring the victim so much they die of fright.

It protects you from being harmed by negative energy.

The second protects against both of those spells, because it protects against instant death caused by magic. This includes having the soul ripped away from the body, but it also includes physical damage to the body that kills it (e.g. implosion). But only if it would do so under any circumstances. So if you get hit by a fireball that would kill you if you fail the save, death ward doesn't protect against that, even though both would be killing you by inflicting unsurvivable damage to your body resulting from you failing a saving throw. It also protects against energy drain and level drain.

It protects you from being harmed by negative enemy, and also protects you against things that would kill you if you failed the save, but only if they would always kill you if you failed the save.

Now let's look at what this requires the spell to do.

The first of these stops negative energy spells from affecting you.
The second also blocks negative energy, but in addition it checks out any other spell coming your way to see if it creates an effect that could kill you, but only if it's designed to do so regardless of how much health you currently have, no matter what mechanism it uses to accomplish this, and if it is does blocks that.

In my opinion, one of these is very simple, and works perfectly well in-universe. The other makes no goddam sense.