Nonliving Critical (3.5e Variant Rule)
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|“||Eiji swung hard against the stone door with his sledgehammer, striking a resounding blow which cracked the surface. Moments later the door crumbled before him.||”|
This rule allows critical hits against that which normally cannot be critted. A DM may with to apply it to inanimate objects only and not to objects and creatures like undead, if they feel it is too strong.
Effectively you may crit an object only on a natural 20, regardless of the weapon's actual modifier. In addition, the critical is always one less than normal. For certain weapons like daggers and rapiers, this does not allow them to have enough force to actual critical a hard, inanimate object like a statue. Other weapons with more weight to them, like axes and picks, obviously deal more. Thus, an Axe deals 20/x2, and a Heavy Pick, 20/x3.