Can spells that stabilise you when you'd die overrule death from exceeding negative constitution?

Question

Characters die from damage when their health is reduced below their negative Constitution score. However, some spells stabilize you when you'd die. Can these spells stabilize you even from damage that reduces your health below your negative Constitution?

For example, Shadow Endurance says:

If you are reduced below 0 hit points or rendered unconscious, shadow endurance immediately discharges, shunting your injured body into a hidden alcove on the Shadow Plane.

You immediately stabilize, but cannot awaken or take any further actions until the second duration expires.

Nine Lives does similar:

Rejuvenate: The target uses this ability when it is reduced to 0 or fewer hit points. The target is instantly healed 3d6 points of damage. If enough hit points are regained to bring the target to positive hit points, it does not fall unconscious. If it is not enough to leave the target with positive hit points, the target automatically stabilizes. Both of these effects work even if the damage was originally enough to kill the target.

I feel it's made fairly clear in the case of nine-lives that you wouldn't die, but it's less clear for me whether it'd work the same way in the case of Shadow Endurance. How do spells that stabilize you from dying interact with outright death? Can they successfully stabilize you, or do you die anyway?

Answer 1

Yes and No.

Let's look at each of the spells in question.

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Shadow Endurance states (emphasis mine):

If you are reduced below 0 hit points or rendered unconscious, shadow endurance immediately discharges, shunting your injured body into a hidden alcove on the Shadow Plane. You immediately stabilize, but cannot awaken or take any further actions until the second duration expires.

So if you're reduced below 0 HP or gain the unconscious condition, the spell triggers and you're sent to the shadow plane where you're stabilized.

Let's see what happens when you get stabilized. (Coincidentally, stabilize actually means nothing in Pathfinder, the actual action is called First Aid.) If we look at the Heal skill we see (emphasis mine):

First Aid: You usually use first aid to save a dying character. If a character has negative hit points and is losing hit points (at the rate of 1 per round, 1 per hour, or 1 per day), you can make him stable. A stable character regains no hit points but stops losing them. First aid also stops a character from losing hit points due to effects that cause bleed (see Conditions for rules on bleed damage).

All stabilizing does is keep you from losing further hit points, so if you took enough damage to bring your total HP to a negative value equal to or greater than your Constitution score, you would still die.

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Nine Lives states (emphasis mine):

Rejuvenate: The target uses this ability when it is reduced to 0 or fewer hit points. The target is instantly healed 3d6 points of damage. If enough hit points are regained to bring the target to positive hit points, it does not fall unconscious. If it is not enough to leave the target with positive hit points, the target automatically stabilizes. Both of these effects work even if the damage was originally enough to kill the target.

This ability of the spell only triggers when you're reduced to 0 HP or less. If you took enough damage to bring your total HP to a negative value equal to or greater than your Constitution score, the healing is still activated (last line). If this would bring you above that threshold, you would continue to stay alive, and be conscious or stabilized depending on the amount of HP you have. If the healing is not enough, you would die.