Rough Edges (3.5e Feat)
From D&D Wiki
Rough Edges [General, Fighter]
You've become accustomed to being struck, and know just how to make it hurt them just as much.
Prerequisite: Con 15
Benefit: When you are struck by a successful attack, you return damage back to the attacker, equal to your constitution bonus.
Normal: Upon being struck, no damage is returned.
Special: If your Con modifier is greater than +10, this also returns damage equal to 1/12 of your HP, rounded down.