Adamantine Bones p. 81
You are an impenetrable tower of defiance on the battlefield. Attacking you is as fruitless as striking a mountain with a walking stick.
The supreme focus, mental toughness, and physical durability taught by the Stone Dragon discipline culminate in this powerful combat maneuver. When you make a successful attack, your mind focuses your body into the equivalent of a living shard of rock. Even the most ferocious attacks bounce off you without harm.
As part of this maneuver, you make a single melee attack. If this attack hits, you gain damage reduction 20/adamantine for 1 round.