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. You can only raise an undead creature's effective Hit Die to one half your caster level through Necromantic feats.
Special: This feat may only be applied to undead that have an intact skeleton (skeletons, zombies, ghouls, but not ghosts, for example).