Regeneration and Dying
*disclaimer* I have not rooted about extensively on the message boards on this topic but I have read some posts and think I know the RAW pretty well. This seems to be the RAW on the topic, with my interpretation as glue 8^)
Regeneration(Ex){monstrous regeneration}
creatures with this ability "cannot die as long as their regeneration is still functioning".
Secondly, "Certain attack forms, typically fire and acid, cause a creature’s regeneration to stop functioning on the round following the attack. During this round, the creature does not heal any damage and can die normally."
So this means that if you drop a critter to negative HP+CON using an attack that is not regenerated, they die the FOLLOWING round, not the round they hit -(HP+CON) or below.
If you drop them with a damage type they can regenerate, they canot die. Now at -(HP+CON or below if you apply damage that stops their regeneration (or presumably they cannot regenerate) able damage, they die the FOLLOWING round.
This seems overly picky until you apply Fast Healing. This would lower the -(HP+CON) boundary to -(HP+CON+FastHeal) as they are going to Fast Heal that 1 round before death.
I'm assuming that death occurs at the end of their round on their initiative. After that it's a moot point, they're dead Jim.
In RAI/usualy play, Bleed damage is usually taken when the attack hits, then it "heals up" and the creature doesn't suffer bleeding afterwards. So in your hypothetical scenario unless you continually stick the regenerating creature it will stop bleeding (taking damage) except in a flavortext way.
This hails back to a troll in a box with a meat grinder attached. By RAW you have an inexhaustible supply of trollburger so long as you leave just a troll tip in the box. Most GMs at some point would say - OK - you've had your fun and the troll dies (mainly due to lack of nourishment on the trolls part). So things don't always go as RAW particularly where free lunches over a long period of gametime are concerned.
Regeneration Spell, Ring of Regeneration, Pearly White Spindle Ioun stone.
ahh yes - works a bit different than the above. Also probably the strongest argument as to why it's better to BE a monster than to imitate one using spells.
Heal 1 lethal and 1 non-lethal per round (no damage type stops it).
Immune to bleed damage.
Losing a limb, etc; 1r with limb, 2d10r without. HPs are NOT addressed in a per limb fashion.
"Regenerate(spell) also cures 4d8 points of damage + 1 point per caster level (maximum +35), rids the subject of exhaustion and fatigue, and eliminates all nonlethal damage the subject has taken."
The Ring description lowers the cure to 1&1 per round.
Exhaustion and Fatigue are not addressed and the Ring text directs the healing text to the limb only. So the Ring does not banish these conditions.
Onto the moment of death. Since this is as the regeneration spell - if you are dead there is no regeneration. But you can regenerate 1&1 per round and there is no damage type that can not be regenerated. Certainly a conundrum if you hit that old -(HP+CON) by damage.
The official line (appeal to authority) is that it IS NOT the same, and that you die at -(HP+CON).
Certainly a good argument could be made that at -(HP+CON) your regeneration goes off and that you die at the end of the following round.
Again, this seems overly picky until you apply Fast Healing. Assuming that death occurs at the end of the round on their initiative when at negative (HP+CON) {see Fast Healing, Breath of Life}. This would lower the -(HP+CON) boundary to -(HP+CON+FastHeal) as they are going to Fast Heal that 1 round before death.
As we are talking about death, Coup deGrace usually happen after a creature is unconscious and dying. So long as the creature has monstrous regeneration they just go more negative in HPs. The spell type would be susceptible to the failed save and then regeneration and such would cease.
