Olgar Shiverstone
Legend
If the character takes damage, he dies (oh, wait, that's the lava rules ...).
Perhaps: When you hit zero hit points or below, your character falls unconscious. Roll an attack against your Fort Defense (D20 vs Fort). If it fails, you remain unconscious. If it succeeds, you die. If you roll a natural "1", you wake up with 25% HP. You make this roll only once, unless you take additional damage after falling onconscious, in which case you must make this roll each time you fall unconscious. Result: Easy to remember, death is still possible, uses the "Defense"-style saves, and gives tougher characters (high Con, etc) a benefit. As Fort Defense increases, the character might only have a 1-in-20 chance of dying (on a natural 20).
Another alternate: Unconscious but stable at 0 hp, dying at negative hp, death at - 1/2 hp. You lose d(HD) hit points each round (e.g, d8 for cleric) until you are stabilized by a teammate. Result: dying is much scarier, and quicker, and puts the onus on stabilizing a character ... on average you have your level in rounds before death. To soften this, you could have [d(HD)-(CON bonus)] lost each round ... so that if you have a good CON bonus, on some rounds you would actually gain hit points (and a godlike character with a high enough Con would regenerate each round in the negatives instead of dying).
If you use action/hero points ... spend an action point at any time to stabilize.
Perhaps: When you hit zero hit points or below, your character falls unconscious. Roll an attack against your Fort Defense (D20 vs Fort). If it fails, you remain unconscious. If it succeeds, you die. If you roll a natural "1", you wake up with 25% HP. You make this roll only once, unless you take additional damage after falling onconscious, in which case you must make this roll each time you fall unconscious. Result: Easy to remember, death is still possible, uses the "Defense"-style saves, and gives tougher characters (high Con, etc) a benefit. As Fort Defense increases, the character might only have a 1-in-20 chance of dying (on a natural 20).
Another alternate: Unconscious but stable at 0 hp, dying at negative hp, death at - 1/2 hp. You lose d(HD) hit points each round (e.g, d8 for cleric) until you are stabilized by a teammate. Result: dying is much scarier, and quicker, and puts the onus on stabilizing a character ... on average you have your level in rounds before death. To soften this, you could have [d(HD)-(CON bonus)] lost each round ... so that if you have a good CON bonus, on some rounds you would actually gain hit points (and a godlike character with a high enough Con would regenerate each round in the negatives instead of dying).
If you use action/hero points ... spend an action point at any time to stabilize.