Death, Healing, and Resting

Death

Death is the ultimate end to a charater, any charater who is killed cannot come back, and even if they are brought back through dark magics and necromancy, they'll never be the same person. Death, even when delayed, cannot be cheated. Zombies are merely a mockary of life and even those with memories are nothing more than shadows of their former selves. Their may be stories of powerful liches and immortal beings, but these are just stories.

At Death's Door

Whenever someone would reach 0 hit points, things aren't looking good. Targets at 0 hp are unconcious and unable to wake up unless they regain hit points. While unconious this way, if the person would loose at least 10 hit points, they permanently die.
If a person is saved before death however, they automatically gain a level of exhaustion. Then, they must make an Endurance Saving Throw DC 15. On a failed save, the target gains another level of Exhaustion.

Wound Recovery

Whenever you would gain a wound, it'll generally last with you for a long time, and certain wounds are permanent. Different Wounds take Different amounts of time to heal for and some wounds can be repaired with magic.

Broken Joint Recovery

A broken joint takes 2d6 days to recover from. Every day spent with a long rest, they pass another day. After half the days past, the penalities on the wounds are only half round down.
Whenever you would cast a spell that restores hit points. If a target would gain at least three hit point from healing in under a minute, they restore any single Broken Joint.

Broken Bone Recovery

A broken bone varies. The recovery process can only begin once a cast is put on the area. To apply the cast, it requires a DC 10 Medicine Check. After half the days past, the penalities on the wounds are only half round down.
Broken Hand: 2d6 + 4 days.
Broken Arm or Leg: 4d6 + 30 days.

Using a Damaged Limb

Whenever you would use a Damaged Limb, You must make an Endurance Saving Throw DC 10. On a failed save, you get the following conditions.
Broken Joint: You gain 1st tier level of pain. 
Broken Bone: You gain 2nd tier level of pain.