Let's bring ability score damage back to what it is supposed to be instead of this nigh-useless nerf fest we have now.
Ability Score Loss
Some attacks reduce the opponent’s score in one or more abilities. This loss can be temporary (ability damage) or permanent (ability drain).
While any loss is debilitating, losing all points in an ability score can be devastating.
Strength 0 means that the character cannot move at all. He lies helpless on the ground.
Dexterity 0 means that the character cannot move at all. He stands motionless, rigid, and helpless.
Constitution 0 means that the character is dead.
Intelligence 0 means that the character cannot think and is unconscious in a coma-like stupor, helpless.
Wisdom 0 means that the character is withdrawn into a deep sleep filled with nightmares, helpless.
Charisma 0 means that the character is withdrawn into a catatonic, coma-like stupor, helpless.
Keeping track of negative ability score points is never necessary. A character’s ability score can’t drop below 0.
If a character’s Constitution score drops, then he loses 1 hit point per Hit Die for every point by which his Constitution modifier drops. A hit point score can’t be reduced by Constitution damage or drain to less than 1 hit point per Hit Die.
Let's get on making this a thing again.Helpless
A helpless character is paralyzed, held, bound, sleeping, unconscious, or otherwise completely at an opponent’s mercy. A helpless target is treated as having a Dexterity of 0 (-5 modifier). Melee attacks against a helpless target get a +4 bonus (equivalent to attacking a prone target). Ranged attacks gets no special bonus against helpless targets. Rogues can sneak attack helpless targets.
As a full-round action, an enemy can use a melee weapon to deliver a coup de grace to a helpless foe. An enemy can also use a bow or crossbow, provided he is adjacent to the target. The attacker automatically hits and scores a critical hit. (A rogue also gets her sneak attack damage bonus against a helpless foe when delivering a coup de grace.) If the defender survives, he must make a Fortitude save (DC 10 + damage dealt) or die.
Delivering a coup de grace provokes attacks of opportunity.
Creatures that are immune to critical hits do not take critical damage, nor do they need to make Fortitude saves to avoid being killed by a coup de grace.