Possibly a new feat, although the idea is basic and I'm surprised I've not seen something like it before (although I don't have the splatbooks, so perhaps it's in there).
Delay Death (stupid name, but oh well)
Your time from dying to death is longer.
Prerequisite: Con 13+, Toughness
Benefit: When dying (reduced to negative hit points), add your constitution bonus to 10 to get the number of negative hit points reached before death.
Example: A character with an 18 Con would be dying from -1 to -13 hit points and dead at -14.
Normal: A character is dying from -1 to -9 hit points, and deat at -10.
Delay Death (stupid name, but oh well)
Your time from dying to death is longer.
Prerequisite: Con 13+, Toughness
Benefit: When dying (reduced to negative hit points), add your constitution bonus to 10 to get the number of negative hit points reached before death.
Example: A character with an 18 Con would be dying from -1 to -13 hit points and dead at -14.
Normal: A character is dying from -1 to -9 hit points, and deat at -10.