Warforged question

[Klaus]

Diplomacy is Charisma-based, and they already get a Charisma penalty. By the same token, they get a punch at Sense Motive (Wis), Bluff (Cha), Perform (Cha) and all other social-interaction skills. I'd just increase the Sense Motive DC vs. warforged so their "stone faces" are reflected mechanically.