Gritty and simple system for damage and HP

[Sadrik]

Here is my system for making the game a gritty and dangerous place.

Taking Damage
Hit Points represent your stamina, luck and skill during combat and CON is your life force. Characters at zero HP begin to take CON damage when at zero CON they are dead (or unconscious with non-lethal damage). When a character takes CON damage they must make a Fortitude save DC 20, if they fail they become disabled with lethal damage (staggered with non-lethal damage). While disabled if they sustain additional damage and the save is failed again they become unconscious and are dying. While dying roll another save every round or suffer another point of damage.

Stabilizing
A DC 15 Heal skill check or any sort of magical healing will automatically stabilize a dying creature, though it will not bring a creature back to consciousness. Roll a Fortitude save DC 20 every minute to return to consciousness. With someone tending a heal check DC 15 may be used instead.

Creatures without a CON Score
Have 10+HD bonus HP, when their HP are at zero they are destroyed.


I am looking for a critique of the ideas presented here and any additional ideas that can be added to system. In particular I am looking at energy drain, falling and save or die spells. I'll post my own ideas. But most importantly I want the underlying system to work as intended.

[Sadrik]

I am not certain these fit into the system I have outlined above. Please critique these and determine if they do. Thanks.

Energy Drain
An energy drain attack deals two CON damage, instead of giving a negative level. Permanent level loss is dealt with by permanently losing two CON.

Falling
Falling deals 1 CON damage for every 10' fell in addition to the HP damage.

Save or Die Spells
A failed save on a spell that causes death causes CON damage instead. The creature loses all HP and takes CON damage depending on the level of the spell. A 4th level spell deals 7 CON damage, 5th level 9 CON damage, 6th level 11 CON damage, 7th level 13 CON damage, 8th level 15 CON damage and 9th level 17 CON damage.