The thick, sturdy plates of an umber hulk's hide can be used to craft sturdy, powerful armor and shields that offer their wearer protection against psychic attack. Any half plate or shield created with umber hulk hide adds +2 to armor modifier and has immunity: mind affecting spells. The +2 AC bonus does not stack with further enchantment bonuses crafted to the shield or armor; the bonuses overlap. For example, an umber hulk heavy shield with a crafted-on +3 enhancement bonus gives a total of +5 to AC (the shield's base +2, plus the +3 enhancement). Note however, that the immunity to mind-affecting spells remains, making umber hulk still quite valuable (especially for a fighter-type with low will saves).