Grievous Wounds (3.5e Variant Rule)

Grievous Wounds
It is common knowledge that in D&D hit points don't mean anything until they fall below 0. This is highly unrealistic. In reality, as people are wounded they begin to weaken; their wounds overtake them. There have been many attempts to fix this, but the majority of them focus on directly giving penalties when below a certain hit point threshold. This fails to capture the nature of real world combat, as in the real world an especially grievous wound will continue to suffer even after one has returned to the most part to health: torn tendons remain torn, concussions have lasting effects. This variant rule attempts to provide rules for those who wish to simulate this in their game. Note that this makes combat more deadly and in that way hurts melee more than caster types, and if that bothers you, you should not effect this variant.

At the end of any round during which you are damaged by over one half your current hitpoints you rule a d20, consulting the table below and take 1d4 + 3 * (damage taken / max hitpoints) (round down) ability damage to the corresponding score.

If several abilities have the same score and one would be rolled, your DM chooses which to damage.