You can continue to fight even while gravely injured.
Prerequisites
Benefit
When reduced to negative hit points, you automatically become stable. You don’t have to make a check each round to avoid losing additional hit points. You may choose to act as if you were disabled, rather than dying. You must make this decision as soon as you are reduced to negative hit points (even if it isn’t your turn). If you do not choose to act as if you were disabled, you immediately fall unconscious.
When using this feat, you are staggered. You can take a move action without further injuring yourself, but if you perform any standard action (or any other action deemed as strenuous, including some free actions, swift actions, or immediate actions, such as casting a quickened spell) you take 1 point of damage after completing the act.
If your negative hit points are equal to or greater than your Constitution score, you immediately die.