Iron Skeleton (3.5e Feat)
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Iron Skeleton [Necromantic]
Undead you create have their skeleton structure reinforced by iron
Prerequisite: Able to raise or create undead
Benefit: When you raise or create an undead creature you may choose to add a 10 lbs of iron and an emerald worth at least 25 gp to the material components of the spell. If you do, the undead creature gains 2 hitpoint per Hit Die. A skeleton created with this feat also gains +2 natural armor. An undead created in this way counts as one Hit Die higher for the purposes of creating it and controlling it.
Special: This feat may only be applied to undead that have an intact skeleton (skeletons, zombies, ghouls, but not ghosts, for example).