Someone said:2-No, the fat doesn´t mention any ability related with non-lethal damage.
DevoutlyApathetic said:Which of course means the feat does nothing beyond the auto-stablize if you use the RAW.
SRD said:DIEHARD
When reduced to negative hit points, you may choose to act as if you were disabled, rather than dying.
When you take nonlethal damage, keep a running total of how much you’ve accumulated. Do not deduct the nonlethal damage number from your current hit points. It is not “real” damage. Instead, when your nonlethal damage equals your current hit points, you’re staggered, and when it exceeds your current hit points, you fall unconscious. [emphasis in original]
Regeneration (Ex): A creature with this ability is difficult to kill. Damage dealt to the creature is treated as nonlethal damage.
Fieari said:On the other hand, unless the troll is a PC, there's no reason to not make this troll more powerful than other trolls by effectively giving it 10 more non lethal hp on top of the Die Hard feat.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.