Your body is overlaid with hundreds of protruding spikes that can deal great damage to foes.
Benefit: You deal extra piercing damage on a successful grapple attack as if you were wearing armor spikes (1d6 points for a Medium warforged). Though you slam attack deals no extra damage, the damage that it deals is treated as both bludgeoning and piercing damage.
This effect of this feat doesn’t stack with equipment or abilities that provide similar benefits. (such as the warforged juggernaut’s armor spikes).