Can a Half-Orc's Relentless Endurance trait save it from its soul being stolen when it dies?

Question

Half-Orcs have the Relentless Endurance racial trait:

Relentless Endurance. When you are reduced to 0 hit points but not killed outright, you can drop to 1 hit point instead. You can't use this feature again until you finish a long rest.

So what happens if a Half-Orc is directed by an effect that steals its soul if it dies, such as (but not limited to) soul cage?

The description of soul cage says:

This spell snatches the soul of a humanoid as it dies and traps it inside the tiny cage you use for the material component.

If the Half-Orc dies, then this spell could be used as a reaction. If the Half-Orc dies, what would happen first? Would the soul cage steal the soul, or would the Relentless Endurance happen first and the Half-Orc would remain alive?

Answer 1

Relentless Endurance does not trigger if you die.

Relentless Endurance states:

When you are reduced to 0 hit points but not killed outright, you can drop to 1 hit point instead. You can’t use this feature again until you finish a long rest.

Soul cage has a casting time of 1 Reaction:

which you take when a humanoid you can see within 60 feet of you dies

If you are using Relentless Endurance, at no point are you dead, so at no point are you an eligible target for soul cage. If you are dead, then you can't use Relentless Endurance, and would be an eligible target for soul cage.

Soul cage only works when a humanoid dies, Relentless Endurance only triggers when you don't die, so there is no interaction between these two features.

To answer the question directly, Relentless Endurance can indirectly protect you from soul cage by possibly delaying your death, as instead of being knocked unconscious and rolling death saves when you reach 0 hit points, you instead have 1 hit point.