Tough Guy (3.5e Feat)
From D&D Wiki
 Tough Guy [Archetype]
Through a life of taking blows, you have hardened your body to a fine degree.
Prerequisite: Con 16+
Benefit: See below
Special: If you ever stop qualifying for this feat, you can trade it for another archetype feat you meet the prerequisites.
Archetype Feat Bonus are based on HD.
- 1 HD: Your hit die increase by 1 step (1d4 to 1d6, 1d6 to 1d8, etc). If you already have a d12 hit die, you gain +2hp per level instead.
- 3 HD: You can enchant your body as though it were armor. You also gain a natural armor bonus equal to one third of your HD (rounded up), as long as you're not wearing any armour.
- 8 HD: You gain DR/- equal to 1/2 your constitution modifier whenever you are not wearing armour.
- 15 HD: You gain fast healing equal to 1/2 your constitution modifier.