How do the temporary HP from Greater Tenacity actually work?

Question

I'm interested in the Bodyguard archetype for my animal companion. Although I'm not high level enough for now, I want a few clarifications on the Greater Tenacity ability, and above all on the temporary hit points gained from it :

At 15th level, a bodyguard with fewer than 0 hit points gains a +4 morale bonus on attack rolls, saving throws, and skill checks; immunity to fear effects; and temporary hit points equal to its master's class level (maximum 20). It dies only if its hit points reach a negative total equal to twice its Constitution score + its master's class level.

This ability replaces improved evasion.

Do these temporary hit points last indefinitely if my animal companion stops taking damage and is healed above 0 HP ? Does the 1HP/round health loss from being below 0 HP decrease these temporary HP before actual HP ?

Answer 1

No duration was given, so those temporary hit points lasts until she healed back above 0 hit points, or she dies.

Example: Your 10th level pet was struck by an ogre's club and went down to -5 hit points, the Tenacity ability kicks in and it imediatelly gets 10 temporary hit points.

If your pet is healed above 0 hit points, she is no longer dying, as her actual hit points are above 0. And her temporary hit points disapear, as the ability's condition was lost:

a bodyguard with fewer than 0 hit points

Just keep in mind that if your pet happens to go under 0 hit points again, the total temporary hit points will not increase, it remains capped at 10 (the master's level).

All damage should be taken from temporary hit points first.

According to the rules for temporary hit points.

Certain effects give a character temporary hit points. These hit points are in addition to the character's current hit point total and any damage taken by the character is subtracted from these hit points first. Any damage in excess of a character's temporary hit points is applied to his current hit points as normal. If the effect that grants the temporary hit points ends or is dispelled, any remaining temporary hit points go away. The damage they sustained is not transferred to the character's current hit points.

When temporary hit points are lost, they cannot be restored as real hit points can be, even by magic.

When your character is under 0 hit points total, she is Dying until he recieves healing or is stabilized with a Heal DC 15 check. Temporary hit points are not healing, it is simply hit points that should be taken before your actual hit points, as a second health that covers your actual health from taking damage.

So your pet is still dying and losing 1 hit point per round until she recieves at least 1 point of healing, is stabilized, or dies. The temporary hit points are not affected, but will delay her death if he takes any kind of damage, even this hit point loss, it will even prevent her from bleeding to death again if she was made stable and then wounded again.

This loss of hit points work just as regular damage.

This seems to be backed by James Jacobs on this post. But to sum it up:

• They regain consciousness if the temporary hit points would put them at or over an effective hp of zero.
• They do not stabilize, so they continue to lose 1 hp per round until they stabilize.
• They lose 1 hp per round, but they lose hp first from temporary hit points.

Answer 2

The temporary hit points—like the listed bonuses—from the extraordinary ability greater tenacity that's possessed by a level 15 or higher master's animal companion with the archetype bodyguard remain only while the animal companion is below 0 hp. Such an animal companion that gains hp sufficient to put it at 0 hp or higher loses the benefits of greater tenacity, including the temporary hit points!

Examples

• A level 15 master's animal companion with the bodyguard archetype is dealt damage sufficient to reduce the animal companion to −20 hp while the master isn't adjacent to the animal companion. The extraordinary ability greater tenacity activates, and the animal companion gains 15 temporary hp so that it's still at −5 hp. The animal companion is dying.

• A level 15 master's animal companion with the bodyguard archetype is dealt damage sufficient to reduce the animal companion to −20 hp while the master is adjacent to the animal companion. The extraordinary ability greater tenacity activates, and the animal companion gains 15 temporary hp so that it's still at −5 hp. Because of the extraordinary ability tenacious guardian, the animal companion is dying (and, if the GM so rules, due to the special ability tenacious guardian, losing an additional 1 hp per round), yet the animal companion remains conscious, merely staggered.

An effect that heals the animal companion's hp to above 0 (or a different effect that increases the animal companion's hp above 0 due to temporary hp) causes the animal companion to lose any remaining temporary hp from the special ability greater tenacity. This can reduce the animal companion below 0 hp again, reactivating the special ability greater tenacity!

Such an animal companion can get caught in a loop wherein the animal companion is repeatedly gaining enough temporary hp so it has at least 0 hp then, because it possesses at least 0 hp, losing those temporary hp, putting the animal companion below 0 again. In such a case, this GM would rule that the temporary hp are gained and wouldn't be gained again until the creature was again reduced below 0 hp through damage dealt or other means. (In Magic: The Gathering a judge would be called over to resolve the ambiguity.)

Temporary hp are just like regular hp except they're lost first. While a creature has any positive hp (its own or temporary), the creature's neither disabled nor dying. Further, if a creature possessing temporary hp is dying, hp lost because it's dying are subtracted from temporary hp first.