This enables a function which removes you from a game, if your life drops below a certain level.

 

While playing Diablo, and especially when going up against one of the major Bosses, it is crucial to keep your focus on the game.  This can be difficult at certain times:  Food starts to boil over (or catches on fire) on the stove, the dog suddenly decides that the best way to get your attention is to quietly gnaw your foot off, or some well-meaning family member decides that this is the perfect time to discuss something with you.  In any case, there can be very legitimate reasons for losing your train of thought, and allow your life to slip down to a dangerous level.  By setting Chicken Life (another command), you can tell the program at what point to leave the game.  This will not prevent you from dying, because if you are hit hard enough, you can go from a number above Chicken Life to zero, in which case you are just dead.  So the number you put into Chicken Life can be very important.  You don't want to leave the game every five minutes, and yet you don't want to die.  Tough choices.  I always set this on, with no toggle key.